System and method for channel measurement and interference measurement in wireless network

ABSTRACT

An embodiment method, by a user equipment (UE), includes performing a channel measurement (CM) on a first subset of a set of non-zero-power (NZP) CSI reference signal (CSI-RS) resources and an interference measurement (IM) on at least a second subset of the set of NZP CSI-RS resources. The second subset includes one or more NZP CSI-RS ports. The IM is performed according to assumptions: each NZP CSI-RS port in the second subset corresponds to an interference transmission layer, the IM being in accordance with a set of energy per resource element ratios each associated with one NZP CSI-RS resource in the second subset; and other interference not associated with the interference transmission layers is on the first and second subsets. The method includes generating a channel state information (CSI) report based on the CM and IM and transmitting the CSI report to a network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/422,534, filed on May 24, 2019, now U.S. Pat. No. 11,399,299 issuedon Jul. 26, 2022, entitled “System and Method for Channel Measurementand Interference Measurement in Wireless Network,” which is acontinuation of International Application No. PCT/US2018/061558, filedon Nov. 16, 2018, entitled “System and Method for Channel Measurementand Interference Measurement in Wireless Network,” which claims priorityto U.S. Provisional Application No. 62/588,176, filed on Nov. 17, 2017,entitled “System and Method for Channel Measurement and InterferenceMeasurement in Wireless Network,” and of U.S. Provisional ApplicationNo. 62/670,464, filed on May 11, 2018. The disclosures of theaforementioned applications are hereby incorporated by reference intheir entireties.

TECHNICAL FIELD

This disclosure relates to systems and methods for wirelesscommunications, and, in particular embodiments, to a system and methodfor channel measurement in wireless network.

BACKGROUND

Wireless communication systems include long term evolution (LTE), LTE-A,LTE-A-beyond systems, 5G LTE, 5G New Radio (NR), etc. A modern wirelesscommunications system may include a plurality of NodeBs (NBs), which mayalso be referred to as base stations, network nodes, communicationscontrollers, cells or enhanced NBs (eNBs), and so on. A NodeB mayinclude one or more network points or network nodes using differentradio access technologies (RATs) such as high speed packet access (HSPA)NBs or WiFi access points. A NodeB may be associated with a singlenetwork point or multiple network points. A cell may include a singlenetwork point or multiple network points, and each network point mayhave a single antenna or multiple antennas. A network point maycorrespond to multiple cells operating in multiple component carriers.

An eNB may be interconnected with another eNB via an X2 interface. AneNB may also be connected via an S1 interface to a Mobility ManagementEntity (MME) and to a Serving Gateway (S-GW). Additionally, a cell orNodeB may serve a number of users (also commonly referred to as UserEquipment (UE), mobile stations, terminals, devices, and so forth) overa period of time. Network resources include a point, network point,transmission point (TP), transmission-reception point (TRP), node,network node, etc., to serve UE. Such network resources may bephysically distributed or localized, and at a location there may be oneor more sets of such resources (e.g., one or more network points). Anetwork resource may act as a virtualized cell to a UE. The network orthe UE may have multiple layers. Generally, Layer 1 is the physical(PHY) layer, Layer 2 is the medium access control (MAC) layer, Layer 3the RRC layer, etc.

Generally speaking, in orthogonal frequency division multiplexing (OFDM)systems, the frequency bandwidth of the system is divided into multiplesubcarriers in the frequency domain. In the time domain, one subframe isdivided into multiple OFDM symbols. The OFDM symbol may have a cyclicprefix to avoid the inter-symbol interference caused by multi-pathdelays. One resource element (RE) is defined by the time/frequencyresource within one subcarrier and one OFDM symbol. In a downlinktransmission, reference signals (RSs) and other signals such as a datachannel (e.g., a physical downlink shared channel (PDSCH)), a controlchannel (e.g., a physical downlink control channel (PDCCH)), and anenhanced PDCCH (EPDCCH) are orthogonal and multiplexed in different REsin the time/frequency domain. In an uplink transmission, physical uplinkshared channel (PUSCH) and physical uplink control channel (PUCCH) areorthogonal and multiplexed in different time/frequency resources. A setof REs are grouped together to form a resource block (RB). For example,12 subcarriers in a slot make up a RB.

Generally, to provide any data channels in either uplink (UL) ordownlink (DL) transmissions such as PDSCH or PUSCH of an LTE-A system,reference signals are transmitted. There are reference signals for a UEto perform channel/signal estimation/measurements for demodulation ofPDCCH and other common channels as well as for some measurements andfeedback, which is the Common/Cell-specific Reference Signal (CRS)inherited from the Release 8/9 specification of Evolved UniversalTerrestrial Radio Access (E-UTRA). A Dedicated/Demodulation ReferenceSignal (DMRS) may be transmitted together with the PDSCH channel inRelease 10 of E-UTRA. DMRS is used for channel estimation during PDSCHdemodulation. In Release 10, the Channel State Information ReferenceSignal (CSI-RS) is introduced in addition to CRS and DMRS. CSI-RS isused for Release 10 UEs to measure the channel status, especially formultiple antennas cases. PMI/CQI/RI and other feedback information maybe based on the measurement of CSI-RS for Release 10 and beyond UEs. PMIis the precoding matrix indicator, CQI is the channel quantityindicator, and RI is the rank indicator of the precoding matrix. CSI-RSin Release 10 may support up to 8 transmission antennas while CRS maysupport up to 4 transmission antennas in Release 8/9. The number ofCSI-RS antenna ports may be 1, 2, 4, or 8. In addition, to support thesame number of antenna ports, CSI-RS has a lower overhead due to its lowdensity in time and frequency.

A heterogeneous network (HetNet) comprises high power macro points andvarious lower power points that generally may share the samecommunication resources. The lower power points may include, but are notlimited to, picos, micros, remote radio heads (RRHs), femtos (or homeeNBs (HeNBs)), access points (APs), distributed antennas (DAs), relays,and near field communication points.

A network also may comprise several component carriers operating indifferent frequency bands. High frequency bands generally have a highpathloss over distance so they are more suitable to serve a relativelysmaller area, such as being used for high throughput purposes for nearbyUEs. Low frequency bands generally have low pathloss over distance sothey are more suitable to serve a relatively large area, such as beingused for providing coverage.

SUMMARY

According to one aspect of this disclosure, a method, by a userequipment (UE) for wireless communications, includes performing achannel measurement associated with a channel state information (CSI)report on a first subset of a set of non-zero-power (NZP) CSI referencesignal (CSI-RS) (NZP CSI-RS) resources. The method further includesperforming an interference measurement associated with the CSI report onat least a second subset of the set of NZP CSI-RS resources. The secondsubset of the set of NZP CSI-RS resources includes one or more NZPCSI-RS ports. The interference measurement is performed according toassumptions comprising that: each NZP CSI-RS port in the second subsetof the set of NZP CSI-RS resources corresponds to an interferencetransmission layer, the interference measurement being in accordancewith a set of energy per resource element (EPRE) ratios each associatedwith one NZP CSI-RS resource in the second subset of the set of NZPCSI-RS resources; and other interference not associated with aninterference transmission layer to which an NZP CSI-RS port in thesecond subset of the set of NZP CSI-RS resources corresponds is on thefirst subset of the set of NZP CSI-RS resources and the second subset ofthe set of NZP CSI-RS resources. The method further includes generatingthe CSI report based on the channel measurement and interferencemeasurement and transmitting the CSI report to a network.

Optionally, in any of the preceding aspects, the CSI report includes atleast a channel quality indicator (CQI) but not a precoding matrixindicator (PMI).

Optionally, in any of the preceding aspects, each EPRE ratio in the setof EPRE ratios that are each associated with one NZP CSI-RS resource inthe second subset of the set of NZP CSI-RS resources specifies anassumed ratio of a physical downlink shared channel (PDSCH) EPRE to anEPRE of an NZP CSI-RS signal on the NZP CSI-RS resource.

Optionally, in any of the preceding aspects, the method further includesreceiving a configuration of a set of resources for CSI interferencemeasurement (CSI-IM) and the assumptions according to which theinterference measurement is performed further include that otherinterference not associated with an interference transmission layer towhich an NZP CSI-RS port in the second subset of the set of NZP CSI-RSresources corresponds is on the set of resources for CSI-IM.

Optionally, in any of the preceding aspects, the method further includesreceiving a configuration of measurement restriction associated withchannel measurement.

Optionally, in any of the preceding aspects, the method further includesreceiving a configuration of measurement restriction associated withinterference measurement.

Optionally, in any of the preceding aspects, the first subset of the NZPCSI-RS resources and the second subset of the NZP CSI-RS resourcesoverlap.

Optionally, in any of the preceding aspects, the method further includesreceiving, by the UE from a network node, an indication of the set ofNZP CSI-RS resources for the channel measurement and the interferencemeasurement. The indication indicates the first subset of the NZP CSI-RSresources and the second subset of the NZP CSI-RS resources.

Optionally, in any of the preceding aspects, the network node includes aNodeB, an evolved NodeB (eNB), or a next generation NodeB (gNB).

Optionally, in any of the preceding aspects, the UE receives from thenetwork node the indication of the first subset of the NZP CSI-RSresources and the second subset of the NZP CSI-RS resources via downlinkcontrol information (DCI).

Optionally, in any of the preceding aspects, the UE receives from thenetwork node the indication of the first subset of the NZP CSI-RSresources and the second subset of the NZP CSI-RS resources via acombination of downlink control information (DCI) and media accesscontrol (MAC) signaling.

Optionally, in any of the preceding aspects, the DCI provides a dynamictriggering of one or more CSI reporting settings.

According to another aspect of this disclosure, a device (e.g., a userequipment (UE)), includes one or more processors and a non-transitorycomputer-readable storage medium storing programming for execution bythe one or more processors, the programming includes instructions toperform the method in any of the preceding aspects.

According to another aspect of this disclosure, a non-transitorycomputer-readable storage medium stores programming for execution by oneor more processors, the programming including instructions to performthe method in any of the preceding aspects.

According to another aspect of this disclosure, an apparatus (e.g., auser equipment (UE)) for wireless communication includes means forperforming a channel measurement associated with a channel stateinformation (CSI) report on a first subset of a set of non-zero-power(NZP) CSI reference signal (CSI-RS) (NZP CSI-RS) resources. Theapparatus further includes means for performing an interferencemeasurement associated with the CSI report on at least a second subsetof the set of NZP CSI-RS resources. The second subset of the set of NZPCSI-RS resources includes one or more NZP CSI-RS ports. The interferencemeasurement performed according to assumptions comprising that: each NZPCSI-RS port in the second subset of the set of NZP CSI-RS resourcescorresponds to an interference transmission layer, the interferencemeasurement being in accordance with a set of energy per resourceelement (EPRE) ratios each associated with one NZP CSI-RS resource inthe second subset of the set of NZP CSI-RS resources; and otherinterference not associated with an interference transmission layer towhich an NZP CSI-RS port in the second subset of the set of NZP CSI-RSresources corresponds is on the first subset of the set of NZP CSI-RSresources and the second subset of the set of NZP CSI-RS resources. Theapparatus further includes means for generating the CSI report based onthe channel measurement and interference measurement and means fortransmitting the CSI report to a network.

According to another aspect of this disclosure, a method, by a networknode for wireless communications, includes indicating, by the networknode to a user equipment (UE), a set of non-zero-power (NZP) channelstate information (CSI) reference signal (CSI-RS) (NZP CSI-RS) resourcesfor channel measurement and interference measurement. A first subset ofthe set of NZP CSI-RS resources are configured for channel measurement,and a second subset of the set of NZP CSI-RS resources are configuredfor interference measurement. The method further includes receiving, bythe network node, a CSI report from the UE. The CSI report is based onthe channel measurement and interference measurement, the channelmeasurement having been performed by the UE on the first subset of theset of NZP CSI-RS resources and the interference measurement having beenperformed by the UE on the second subset of the set of NZP CSI-RSresources and according to assumptions comprising that: each NZP CSI-RSport in the second subset of the set of NZP CSI-RS resources correspondsto an interference transmission layer, the interference measurementbeing in accordance with a set of energy per resource element (EPRE)ratios each associated with one NZP CSI-RS resource in the second subsetof the set of NZP CSI-RS resources; and other interference notassociated with an interference transmission layer to which an NZPCSI-RS port in the second subset of the set of NZP CSI-RS resourcescorresponds is on the first subset of the set of NZP CSI-RS resourcesand the second subset of the set of NZP CSI-RS resources.

Optionally, in any of the preceding aspects, the CSI report includes atleast a channel quality indicator (CQI) but not a precoding matrixindicator (PMI).

Optionally, in any of the preceding aspects, each EPRE ratio in the setof EPRE ratios that are each associated with one NZP CSI-RS resource inthe second subset of the set of NZP CSI-RS resources specifies anassumed ratio of a physical downlink shared channel (PDSCH) EPRE to anEPRE of an NZP CSI-RS signal on the NZP CSI-RS resource.

Optionally, in any of the preceding aspects, the method further includesindicating, by the network node to the UE, a configuration of a set ofresources for CSI interference measurement (CSI-IM) and the assumptionsaccording to which the interference measurement is performed furthercomprise that other interference not associated with an interferencetransmission layer to which an NZP CSI-RS port in the second subset ofthe set of NZP CSI-RS resources corresponds is on the set of resourcesfor CSI-IM.

Optionally, in any of the preceding aspects, the method further includesindicating, by the network node to the UE, a configuration ofmeasurement restriction associated with channel measurement.

Optionally, in any of the preceding aspects, the method further includesindicating, by the network node to the UE, a configuration ofmeasurement restriction associated with interference measurement.

Optionally, in any of the preceding aspects, the network node comprisesa NodeB, an evolved NodeB (eNB), or a next generation NodeB (gNB).

Optionally, in any of the preceding aspects, the first subset of the NZPCSI-RS resources and the second subset of the NZP CSI-RS resourcesoverlap.

Optionally, in any of the preceding aspects, the network node indicatesto the UE the first subset of the NZP CSI-RS resources and the secondsubset of the NZP CSI-RS resources via downlink control information(DCI).

Optionally, in any of the preceding aspects, the network node indicatesto the UE the first subset of the NZP CSI-RS resources and the secondsubset of the NZP CSI-RS resources via a combination of downlink controlinformation (DCI) and media access control (MAC) signaling.

Optionally, in any of the preceding aspects, the DCI provides a dynamictriggering of one or more CSI reporting settings.

According to another aspect of this disclosure, a device (e.g., anetwork node), includes one or more processors and a non-transitorycomputer-readable storage medium storing programming for execution bythe one or more processors, the programming includes instructions toperform the method in any of the preceding aspects.

According to another aspect of this disclosure, a non-transitorycomputer-readable storage medium stores programming for execution by oneor more processors, the programming including instructions to performthe method in any of the preceding aspects.

According to another aspect of this disclosure, an apparatus (e.g., anetwork node) for wireless communications, includes means forindicating, to a user equipment (UE), a set of non-zero-power (NZP)channel state information (CSI) reference signal (CSI-RS) (NZP CSI-RS)resources for channel measurement and interference measurement. A firstsubset of the set of NZP CSI-RS resources are configured for channelmeasurement, and a second subset of the set of NZP CSI-RS resources areconfigured for interference measurement. The apparatus further includesmeans for receiving a CSI report from the UE. The CSI report is based onthe channel measurement and interference measurement, the channelmeasurement having been performed by the UE on the first subset of theset of NZP CSI-RS resources and the interference measurement having beenperformed by the UE on the second subset of the set of NZP CSI-RSresources and according to assumptions comprising that: each NZP CSI-RSport in the second subset of the set of NZP CSI-RS resources correspondsto an interference transmission layer, the interference measurementbeing in accordance with a set of energy per resource element (EPRE)ratios each associated with one NZP CSI-RS resource in the second subsetof the set of NZP CSI-RS resources; and other interference notassociated with an interference transmission layer to which an NZPCSI-RS port in the second subset of the set of NZP CSI-RS resourcescorresponds is on the first subset of the set of NZP CSI-RS resourcesand the second subset of the set of NZP CSI-RS resources.

Embodiments of this disclosure may provide one or more technicaladvantages. In certain embodiments, configuring NZP CSI-RS resources forinterference measurement provides improved link adaptation performance.Certain embodiments facilitate use of a higher spectrum frequency.Certain embodiments provide improved performance that is suitable foruse with multiple-input and multiple-output (MIMO) and massive MIMOsystems. Link adaptation according to certain embodiments of thisdisclosure allows interference measurement resources at a time, n, toreflect multi-user interference at a time n+k, with a channelmeasurement resource of a first UE being an interference measurementresource of a second UE, which may be advantageous in a multi-user MIMOsystem. Certain embodiments may improve performance in an interferencelimited network, wherein the inter-cell interference is strong and/orwith significant fluctuation, carrier aggregation/channel aggregation,and in coverage enhancement.

Certain embodiments of the present disclosure may provide some, all, ornone of the above advantages. Certain embodiments may provide one ormore other technical advantages, one or more of which may be readilyapparent to those skilled in the art from the FIGS., descriptions, andclaims included in this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, and the advantagesthereof, reference is now made to the following descriptions taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates an example system for turning on or off a networkpoint, according to certain embodiments of this disclosure;

FIG. 2 illustrates an example system in interference from an eNB to arelay exists, according to certain embodiments of this disclosure;

FIG. 3 illustrates method of Transition Adjustment Process, according tocertain embodiments of this disclosure;

FIG. 4 illustrates a transition adjustment period timeline, according tocertain embodiments of this disclosure;

FIG. 5 illustrates a transition adjustment period timeline, according tocertain embodiments of this disclosure;

FIG. 6 illustrates state transitions for a point, according to certainembodiments of this disclosure;

FIG. 7 illustrates an example system diagram, according to certainembodiments of this disclosure;

FIG. 8 illustrates an example of probing operation, according to certainembodiments of this disclosure;

FIG. 9 illustrates a flow diagram of CE operation, according to certainembodiments of this disclosure;

FIG. 10 illustrates a flow diagram of eNB operation, according tocertain embodiments of this disclosure;

FIG. 11 illustrates a flow diagram of UE operation, according to certainembodiments of this disclosure;

FIG. 12 illustrates an example of a probing-based link adaptationprocedure, according to certain embodiments of this disclosure;

FIG. 13 illustrates an example of probing for link adaptation, accordingto certain embodiments of this disclosure;

FIG. 14 illustrates an embodiment procedure for probing for linkadaptation, according to certain embodiments of this disclosure;

FIG. 15 illustrates details of an embodiment procedure for probing forlink adaptation, according to certain embodiments of this disclosure;

FIG. 16 illustrates an example of Alt3 from a UE point of view,according to certain embodiments of this disclosure;

FIG. 17 illustrates an example of resources for CSI measurements withCSI-IM not covered by adjacent eNBs' ZP CSI-RS resources, according tocertain embodiments of this disclosure;

FIG. 18 illustrates an example of resources for CSI measurements withCSI-IM covered by adjacent eNBs' ZP CSI-RS resources, according tocertain embodiments of this disclosure;

FIG. 19 illustrates CSI measurements without CSI-IM and with overlappingCSI-RS, according to certain embodiments of this disclosure;

FIG. 20 shows an example case 2000 for IM based on ZP CSI-RS, accordingto certain embodiments of this disclosure;

FIG. 21 illustrates example of a UE measures the energy/power on a ZPCSI-RS REs, according to certain embodiments of this disclosure;

FIG. 22 illustrates example 2200 on another scenario when IM based onmultiple non-zero-power (NZP) signals and not overlapped with CMR,according to certain embodiments of this disclosure;

FIG. 23 illustrates a typical use case of overlapped CSI-RS resource forchannel and interference, according to certain embodiments of thisdisclosure;

FIG. 24 illustrates an example for non-overlapped CSI-RS resource forchannel and interference measurement, according to certain embodimentsof this disclosure;

FIG. 25 illustrates an inter-cell interference with configuration ofnon-overlapped CMR and interference measurement (IM) resource (IMR),according to certain embodiments of this disclosure;

FIG. 26 illustrates another example configuration of a set of NZP CSI-RSresources, according to certain embodiments of this disclosure;

FIG. 27 illustrates an example method in which a combination of UEbehaviors is implemented, according to certain embodiments of thisdisclosure;

FIG. 28 illustrates an example method 2800 for wireless communication,according to certain embodiments of this disclosure;

FIG. 29 illustrates an example method 2900 for wireless communication,according to certain embodiments of this disclosure;

FIG. 30 illustrates an example communication flow showing multi-usermultiple-input, multiple-output (MU-MIMO) link adaptation based on NZPCSI-RS for interference measurement, according to certain embodiments ofthis disclosure; and

FIG. 31 is a block diagram of a processing system 2700, according tocertain embodiments of this disclosure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the presently preferred embodiments aredescribed in detail below. It should be appreciated, however, that thisdisclosure provides many applicable inventive concepts that may beembodied in a wide variety of specific contexts. The specificembodiments described are merely illustrative of specific ways to makeand use the disclosure, and do not limit the scope of the disclosure.

Various embodiments are motivated by one or more issues emerging fromwireless networks as described below. A network point in a wirelessnetwork may be turned on or off based on traffic demand, energyconstraints, emission constraints, quality of service (QoS) constraints,interference management purposes, or other suitable factors. Oneembodiment solution for handling such an event is based on UL TransitionRequest Signals (TRS) sent by a group of UEs so that the network maydetermine whether it is beneficial to turn on a turned-off networkpoint.

FIG. 1 illustrates an example system 100 for turning on or off a networkpoint, according to certain embodiments of this disclosure. In theillustrated example, if it is decided that Picot 102 is to be turned onor off, UE1 104 and UE2 106, which are both in the Picot 102 coveragearea, may be affected, as well as UE3 108, which is not in the Picot 102coverage area but is not far from Picot 102. UE1 104 and UE2 106 may beconfigured to measure and report Pico2's RS and may hand over to Picot102. In other words, it may be appropriate to reconfigure UE1 104 andUE2 106 based on Pico2's RS. UE3 108 may see increased PDSCHinterference, which may be statistically or qualitatively different fromthe interference previously seen by UE 108. In one example, rather thanbeing due to the normal fluctuations of interference, this increasedinterference seen by UE3 108 may signify, at least in part, a suddenchange of UE3's interference condition, which may entail specialhandling. It may be appropriate to change or reconfigure UE3 108 channelstate information (CSI) (e.g., CQI/PMI/RI) and radio resource management(RRM)/radio link monitoring (RLM) measurement processes and reports. Thenetwork may adjust or fine tune parameters before, during, and/or afterthe transition. The network may evaluate the impact of networkreconfiguration. Further, the network may send reconfiguration signalsto a UE and/or an eNB to facilitate UE reconfiguration. In general, whena configuration of a network point or carrier undergoes a transition,the transition may affect multiple other network points or carriers andmultiple UEs such that it may be appropriate to reconfigure the networkpoints, carriers, or UEs. A procedure to prepare for, support, andhandle the transition and reconfiguration may be desirable.

FIG. 2 illustrates an example system 200 in interference from an eNB toa relay exists, according to certain embodiments of this disclosure. Inthe illustrated example, interference by Macro2 202 to reception byRelay1 204 may increase if Macro2 202 changes its backhaul transmission(Tx) activities. For example, interference may increase if the precodingby Macro2 202 drifts beyond a threshold after some time, if backhaul Txturns on or off due to traffic pattern changes, or if Macro2 202switches from Tx to Relay2 206 to Tx to Relay3 208 due to trafficpattern changes or other changes. These are examples of the networkexperiencing a transition, which may lead to a chain reaction tomultiple network nodes (e.g., multiple network nodes seeing suddeninterference condition changes) for a period of time. As a result of, orin anticipation of, the interference jump, Macros 210 may adjust itstransmission to Relay1 204. This adjustment may further cause changes ofinterference from Macro1 210 to other Macro transmissions. For example,it may be appropriate for Macro2 202 to further adjust (e.g., fine tune)its transmission to Relay2 206 and/or Relay3 208. This chain reaction ofsudden interference jumps may lead the network to adjust itsconfigurations for a period of time. The effect of the adjustments maybe difficult to predict unless the adjustments are actually put intotest in the network. Therefore, an efficient way to support theadjustments without significantly affecting normal data transmissionsmay be desirable.

As another example, algorithms and procedures proposed for networkoptimization may be based on iterations among multiple network nodes,and sometimes multiple UEs are also involved. One example involves thejoint optimization of cell attachment and resource allocation, which maybe difficult to carry out in general and is often performed suboptimallyin an iterative fashion. A suboptimal solution may assume a fixed cellattachment, and then a presumed optimal resource allocation for thegiven cell attachment may be computed. The given resource allocation maybe assumed, and the cell attachment may be further updated. Theseprocedures may be iterated until optimization is achieved or for somemaximum number of iterations. Such iterations, however, may lead tocomplexity and unwanted fluctuations that are not desirable for data(e.g., PDSCH) transmissions. For example, sometimes such an iterativealgorithm may not generate the desired performance or behavior in anumber of iterations. The network configuration obtained after severaliterations may be discarded in such a case, and the network may revertback to the original network configuration. When this situation occurs,the normal data transmissions between multiple network nodes andmultiple UEs may be significantly affected. Therefore, it may bedesirable to separate the resources and processes for normal datatransmission from the iterative probing, optimization, reconfiguration,and adjustment actions. When the iteration achieves convergence on theprobing resources with the desired or acceptable performance orbehavior, the attained configurations may then be applied to PDSCHtransmissions.

The above and similar issues may be summarized as follows. A networkcomponent may often adapt its activity or go through transitions. Forexample, it may be appropriate for a network node, carrier, or antennaset to transition from an activity level (e.g., with reducedtransmission power) or a state (e.g., a dormant state) to a differentactivity level (e.g., with full transmission power) or a different state(e.g., an active state) when traffic, interference, or other conditionschange. As an example, a dormant network node may be turned on when a UEenters the coverage range of the network node. The reconfiguration of afirst network node may affect a number of network nodes and UEs,potentially including the first network node itself, thus generatingtransient dynamics for a period of time. The impact of the transition oradaptation may be evaluated by multiple network nodes and/or UEs before,during, and/or after the transition or adaptation occurs. The proceduremay iterate, where the network node(s) and UEs further adjust or finetune their configurations. When a network node experiences or foresees atransition, the network node may signal its UEs and other network nodesregarding the transition so that the UEs and other network nodes mayknow when to further adapt. Several aspects of this general procedureare described below.

Interference Jump and Reconfiguration Signal to UE

In FIG. 1 , when Picot 102 starts to transmit PDSCH at time t, UE3 108may see increased PDSCH interference statistically or qualitativelydifferent from before. This interference condition change may bedifferent from normal interference fluctuations. Typically UE3 108performs layer 1 filtering for its CQI, interference, Reference SignalReceived Quality (RSRQ), etc. For example, It=f It−1+(1−f) it −1 may beused for interference filtering, where it−1 is the instantaneousmeasurement at time t−1, and It−1 is the filtered measurement at timet−1, and f is the filter constant, normally 0.7-0.99. It may take awhile for the filter to converge to the new interference condition,particularly if the interference measurement is based on CSIinterference measurement (CSI-IM) resources, which are sparse in time.

For example, if the filter constant f is 0.9, then the filter timeconstant is 9.5 samples. In a particular example, it takes approximately2 to approximately 3 times the time constant for the filter to settle toapproximately 85% to approximately 95% of new filtered values. In otherwords, in some scenarios, CRS-based interference measurements take about19 milliseconds (ms) to about 28 ms to settle. Similar computations mayshow that CSI-IM resource-based measurements take about 95 ms to about142 ms to settle if the CSI-IM resource has a period of 5 ms, (e.g.,once in 5 ms). The CSI-IM resource-based measurements take about 190 msto about 285 ms (or about 380 ms to about 570 ms, or about 760 ms toabout 1140 ms, respectively) to settle if the CSI-IM resource has aperiod of 10 ms (or 20 ms, or 40 ms, respectively). These delays maycause the network to respond slowly to the interference jump, and thelong transient period may see some degradation of user experience. Inparticular, CQI/PMI/RI feedback and/or RSRQ measurements may beaffected, causing mismatches in CQI and RSRQ, and hence the transmissionto the UE may become less efficient. A smaller filter constant f may bechosen to reduce the latency, but sensitivity to normal fluctuations maybe too great if the smaller filter constant is used. Therefore, areconfiguration signal sent by the network to a UE to notify the UE of achange of measurement conditions may facilitate UE reconfiguration andnetwork operations. For example, the UE may reset its filter state uponreceiving the signal (e.g., the UE may restart the CSI-IM resource-basedmeasurement process), or the UE may adjust its filter constant to asmaller value. If the UE is signaled to adjust its filter constant to asmaller value, the UE may receive another signal later indicating thecompletion of the transition or reconfiguration, and the UE may adjustits filter to the original value. In other words, the network may usereconfiguration signals to configure the UE to adapt the filteraccording to environment changes.

A UE performs layer 3 filtering for Reference Signal Received Power(RSRP) and RSRQ (Received Signal Strength Indicator (RSSI)). In somescenarios, the accuracy of RSRP layer 3 filtering may be affected whenan interference condition changes, although it may or may not beappropriate to reset the RSRP layer 3 filtering when an interferencecondition changes. For example, when the interference level is normal,RSRP accuracy may be at a first level. When the interference jumps to amuch higher level, RSRP accuracy may degrade to a second level. It maybe useful for the network and UE to know and incorporate the performancechanges due to network condition changes, so that the UE may adapt itsRSRP estimate and filtering according to interference condition changes.Additionally or alternatively, RSRQ layer 3 filtering may be reset whenan interference condition changes. A typical input period to layer 3filtering is about 40 ms, and a default time constant is about 1.5 inputsample durations, so about 2 to about 3 times of the time constant isabout 3 to about 4 input sample durations (about 120 ms to about 160ms). Therefore, if the interference condition takes a sudden jump at atime close to the RSRQ/RSSI reporting time, then the reported RSRQ/RSSImay not reflect the actual interference condition. To facilitate theprocess, a signal to indicate the reset or reconfiguration may be used.If a reset is needed in layer 3 operations, a rule may be createdwherein, upon receiving a reconfiguration signal, the UE resets itslayer 3 filter or temporarily adjusts its filter coefficient.

The above-described layer 3 related values may be computed based onThird Generation Partnership Project (3GPP) Technical Specification (TS)36.331, which is hereby incorporated herein by reference in itsentirety. In TS 36.331, the information element (IE) FilterCoefficientspecifies the measurement filtering coefficient. Value fc0 correspondsto k=0, fc1 corresponds to k=1, and so on.

 FilterCoefficient information element -- ASN1START  FilterCoefficient::= ENUMERATED {fc0, fc1, fc2, fc3, fc4, fc5, fc6, fc7, fc8, fc9, fc11,fc13, fc15, fc17, fc19, spare1, ...}  -- ASN1STOP  QuantityConfigEUTRA::= SEQUENCE {   filterCoefficientRSRP FilterCoefficient  DEFAULT fc4,  filterCoefficientRSRQ FilterCoefficient  DEFAULT fc4}.

The measured result is filtered, before being used for evaluation ofreporting criteria or for measurement reporting, by the followingformula:F _(n)=(1−a)·F _(n-1) +a·M _(n)

where

-   -   Mn is the latest received measurement result from the physical        layer;    -   Fn is the updated filtered measurement result that is used for        evaluation of reporting criteria or for measurement reporting;    -   Fn−1 is the old filtered measurement result, where F0 is set to        M1 when the first measurement result from the physical layer is        received; and    -   a=½(k/4), where k is the filterCoefficient for the corresponding        measurement quantity received by the quantityConfig.

The filter may be adapted such that the time characteristics of thefilter are preserved at different input rates, observing that thefilterCoefficient k assumes a sample rate equal to 200 ms.

Thus, a UE may adapt estimation and/or filtering characteristics basedon the received reconfiguration signals. Additionally or alternatively,since the network has information about the UE's RSRQ/RSSI estimation,filtering, and/or reporting configurations, the network may coordinatethe network components so that a sudden interference change may occur atcertain times depending on the timing of the RSRQ/RSSI estimation,filtering, and/or reporting. For example, the network may allow a nodeto be turned on or off at a fixed offset from the 200 ms-periodRSRQ/RSSI reporting or during a specified time interval different fromthe RSRQ/RSSI reporting.

An eNB may send a network reconfiguration signal to a UE with a specifictiming and associated with a CSI process configuration, CSI-RS resourceconfiguration, and/or CSI-IM resource configuration. UEs very close tothe network node that made the transition are likely to be configured toreceive CSI-RS from that network node. UEs very far from the networknode that made the transition are likely not to be affected by thetransition. It may be appropriate to reconfigure UEs that are in betweenbeing very close to or very far from the network node. Upon reception ofthe reconfiguration signal, UE actions may include resetting filterstates for interference estimation, CSI measurements, and RSRQmeasurements, and adjusting estimation and/or filtering parameters toadapt to an interference condition change. UEs may also start a newsignal or interference measurement process, stop a signal orinterference measurement process, perform handover to another point orcarrier, etc. For brevity, IM is for interference measurement, IMR isfor IM resource, CM is for (intended) channel measurement, and CMR isfor CM resource.

If an eNB does not send a network reconfiguration signal to a UE toinitiate a reconfiguration, the UE may assume a reconfiguration isappropriate when its CSI-RS resources or CSI-IM resources or CSIprocesses (e.g., for a coordinated multipoint (CoMP) set) arereconfigured, such as modified, removed, or added. Generally, assuming agoal of restarting the measurement process on the same resources, thenreconfiguring a CSI process, CSI-RS resource, and CSI-IM resource toachieve that goal may lead to higher overhead than sending areconfiguration signal, which may achieve the same goal. However, ifthere is a timing pattern for the restart of the measurement process, atiming window may be signaled or defined so that the UE may restart themeasurement process at the end of each timing window.

In addition to the overhead concern described above, problems may ariseif a UE attempts to interpret a signal as a measurement reset signal ora filter reconfiguration signal. In other words, there may be situationswhere an explicit measurement reset signal or filter reconfigurationsignal is desirable. For example, for some UEs, using the CSI-RSresource configuration change signal, or CSI-IM resource configurationchange signal, or CSI process configuration change signal, as a networkreconfiguration signal may cause problems. If a UE moves, its CSI-RSresources may naturally update, and its interference condition may nothave any abrupt change, so there may not be always a need to reset itsmeasurement process or reconfigure the filtering parameters and so on,even if the UE's CSI-RS resource configuration is updated. A neighboringUE may, in some scenarios, not experience any CSI-RS resource change,but may still experience a significant interference condition changewhen a network transition occurs. Therefore, cases exist in which theconfiguration of CSI-RS resources, or CSI-IM resources, or CSI processesmay be updated, but in which it may not be appropriate for themeasurement process to be reset or the filter to be reconfigured. Casesin which the CSI-RS resources, and CSI-IM resources, and CSI processesare not updated, but in which there may be a need for the measurementprocess to be reset or the filter to be reconfigured, also may exist.

The reconfiguration signal may or may not be the same as the transitiondecision signal (see, e.g., the signal in Step 304 of FIG. 3 , describedin greater detail below). For example, in one scenario, the transitiondecision signal may turn on only CRS/CSI-RS transmissions. Whether PDSCHtransmissions will occur (which may lead to more interference than RStransmissions alone) may depend on other factors such as CSI feedbackand scheduling. An eNB may send the reconfiguration signal if the eNBchanges its PDSCH activity levels significantly, such as turning onPDSCH based on UE CSI feedback. In other words, the transition decisionand the sudden interference jump may occur at different times, despitethere being some connection between the transition decision and thesudden interference jump. Separating the reconfiguration signal from thetransition decision signal may also reduce or prevent systemoscillation. For example, after an eNB's transition from a dormant stateto an active state, the eNB may receive UE measurement feedback reportsand may decide not to serve the UEs and may even turn off. In such acase, it may or may not be appropriate for neighboring eNBs to signaltheir UEs for reconfiguration and/or to reset their filters. Thereconfiguration signal may be signaled by an upper layer or in the PDCCHor EPDCCH or in a common channel. Timing information may also be sentwith the reconfiguration signal to indicate when the reconfigurationwill be in effect.

Transition Adjustment Period

A network component may often adapt its activity or go throughtransitions. When a network node experiences or foresees a transition,the network node may signal its UEs and other network nodes regardingthe transition so that the UEs and other network nodes may know when andhow to adapt. This signaling may trigger transient dynamics for a periodof time called the Transition Adjustment Period, some procedures ofwhich are described in detail below.

An eNB may send a network reconfiguration signal to neighboring eNBs.Upon reception of the reconfiguration signal, the neighboring eNBs'actions may include reconfiguring their UEs for CSI-RS resources, CSI-IMresources, and/or CSI processes, receiving their UE CSI/RRM/RLM reports,and changing their transmissions/receptions and/or their UEassociations/configurations. The effect of an eNB having made thetransition is evaluated by the network. In some scenarios, the eNBsfurther adjust their transmissions/receptions and their UEassociations/configurations until convergence occurs or according to oneor more exit rules.

A transition at an eNB may cause multiple eNBs to further adjust theirtransmissions/receptions and their UE associations/configurations untilconvergence occurs. The above-described steps may form a procedure forthe network to adjust or fine tune after a transition, and thisprocedure may be referred to as a Transition Adjustment Process. It maybe appropriate to inform a set of eNBs and UEs about this process. Theprocess may be performed on a specific subset of resources (e.g.,probing resources, as described below) or on all relevant resources.Whether the process is performed on probing resources only (which may bea subset of time/frequency resources), or on a larger scale ofresources, may be indicated in the reconfiguration signal.

FIG. 3 illustrates method 300 of Transition Adjustment Process,according to certain embodiments of this disclosure. In step 301, afirst eNB signals a UE about the information of an uplink transmission(via, e.g., PDCCH or EPDCCH). In step 302, the UE performs thetransmission based on the information signaled by the first eNB. In step303, a second eNB performs receiving of the signal transmitted by theUE. In step 304, a third eNB makes a decision on transmission orreception of a fourth eNB, e.g., the possible adaptation of transmissionand reception, and sends reconfiguration signals to other eNBs.

As part of the Transition Adjustment Process, in step 305, the fourtheNB transmits or receives a signal (e.g., Tx CSI-RS, a positioningreference signal (PRS), or other reference signals). In other words, thefourth eNB may be a turned-off eNB that is starting to turn on, or moregenerally, the fourth eNB may be a network entity going through atransition such as on/off, power adaptation, carrier adaptation, orcarrier type adaptation. In step 310 (generally at the end of theTransition Adjustment Process), the fourth eNB transmits or receives asignal (e.g., Tx PDSCH or other data carrying signals). In other words,the fourth eNB may start to serve UEs and engage in data communications,and the transition involving the fourth eNB may be complete.

In step 306, which may be done in parallel to step 305, a fifth eNBsignals to a second UE to receive or transmit (e.g., CSI-RS from thefourth eNB, which has been transmitted starting in step 305, for RRM(RSRP/RSRQ) or CSI measurements). In step 308, the second UE measuresand reports CSI/RRM/RLM to the fifth eNB. At this moment, the second UEis not connected to the fourth eNB, so the communication (of eithercontrol information or data) may take place with the fifth eNB. In step311, the second UE receives (Rx) or transmits (e.g., Rx PDSCH from thefourth eNB, if the measurement reports associated with the fourth eNBled to such a decision) as a result of the Transition AdjustmentProcess. In general, the fifth eNB and the second UE may be close to thefourth eNB, which is going through the transition, and the fifth eNB andthe second UE may be affected by the transition. For example, the secondUE may become connected to and served by the turning-on fourth eNB, andthe fifth eNB may participate in the process of connecting the second UEwith the fourth eNB.

In step 307, a sixth eNB reconfigures and signals to a third UEregarding the reconfiguration. In step 309, the third UE measures andreports CSI/RRM/RLM to the sixth eNB. In general, the sixth eNB and thethird UE may not be close to the fourth eNB, which is going through thetransition process, so the sixth eNB and the third UE may not be asgreatly affected as the components described in steps 306/308/311, butthe sixth eNB and the third UE may still be affected as the third UEexperiences interference transition when the fourth eNB is turning on.To cope with the interference change or in anticipation of this change,reconfiguration of the sixth eNB and the third UE may be done as shownin steps 307/309.

From steps 310, 311 and 309, the eNBs may exchange information over thebackhaul, as shown in step 312. In step 313, the fourth eNB adjuststransmission or reception (e.g., Tx CSI-RS at a different power level).For example, if the fourth eNB transmission power is deemed too high bythe network based on various feedback and measurement reports, thefourth eNB may reduce its transmission power, and the TransitionAdjustment Process may continue until convergence occurs or certaincriteria are achieved.

After the Transition Adjustment Process is complete, in step 314, aseventh eNB signals a reconfiguration signal to a fourth UE, as a newinterference condition (or more generally, a network configuration) isin place. In step 315, the fourth UE performs reconfiguration (e.g.,resets its filters).

The terminologies, timing, and timing order with respect to FIG. 3 maynot be strict, some steps may be skipped, reordered, or changed, andsome terminologies may be generalized or specialized. For example, step304 may be included in the Transition Adjustment Process. The TransitionAdjustment Process (steps 305-313) may be intertwined with the decisionmaking processes (steps 301-304), and may be performed on probingresources only (e.g., in parallel to other normal transmissions) or onall relevant resources. The CSI-RS resource configuration change signal(step 306) and the reconfiguration signal (step 314) may be different ingeneral.

Probing Resources

A probing resource process may be provided, during the TransitionAdjustment Process for example. During the Transition AdjustmentProcess, the eNB with the point that has just been turned on may testseveral different configurations. The testing may be performed byadjusting the power levels (including turning on or off a transmissionpoint and/or a carrier), adjusting the number of ports, adjusting thebandwidth, changing carriers, etc. Such actions may occur in aniterative way. For example, the eNB may transmit at a power level and,based on a UE's feedback, the eNB may increase or decrease the powerlevel. Each power level may lead to a different interference to othereNBs and/or UEs, and therefore the other eNBs and/or UEs may need toadjust their configurations, transmissions, and/or receptions. Theseadjustments may cause a chain reaction that affects the original eNB aswell, and hence more adjustments may be needed. In this process, theUE's PDSCH transmission may be affected. For each adjustment, the eNBmonitors the UE's feedback. The adjustments and feedback may causenetwork operation to fluctuate in an unwanted way, such as the UE mayexperience lower than normal PDSCH transmission rates, such as hundredsof milliseconds. In other words, it may take a long time for the networkto achieve a configuration with suitable and desired performance, andduring that process normal data transmissions may be impacted.

An alternative is to perform a similar procedure in a proactive orprepared way. For example, the system impact or performance may bepredicted on a smaller scale of resources before the transition. Such aprocedure may be done in parallel with the network's normal operations,and thus the normal operations may not be affected. These normaloperations may include normal data transmissions, normal control orsystem information transmissions, normal RRM/RLM/CSI measurements andfeedback, etc. Resources more suitable for the adjustment processes orprobing periods may be defined and/or allocated. The eNBs may configureprobing resources, and may signal the configured probing resources toselected UEs. A selected UE may be configured to measure on the probingresources (for signals and/or interferences) during the same timeperiod, and may report CQI/RRM/RLM measurement reports. The network mayiterate until it finds a suitable transition and a suitableconfiguration after the transition, based on varying the transmissionson the probing resources and the feedback reports. Finally, the networkperforms the transitions. The final transitions are expected to be lessinterruptive and shorter in time since the decided final configurationshave been tested to have the desired performance and/or to correspond toa steady state. Such a procedure may significantly reduce the impact onthe network and the time spent on adjustment or probing processes.

Thus, during the Transition Adjustment Process, it may be useful toutilize probing resources, such as to perform the transition adjustmenton probing resources only. The network may predict the system impactand/or performance before the transition based on measurements on asmaller scale of resources. The measurements related to the predictionmay be made in parallel with the network's normal operations withoutaffecting the network's normal operations. A selected UE may beconfigured to measure the probing resources (for signals and/orinterferences) during the same period, and may report CQIs, RRMmeasurements, RLM measurements, etc. The network may iterate until itfinds a suitable transition and a suitable configuration after thetransition by continuing to adjust the transmissions based on theprobing resources and the feedback reports. Multiple configurations maybe probed in a parallel fashion or sequentially. Finally, the networkperforms the transitions. Such a procedure may significantly reduce theimpact on the network and the time spent on adjustment or probingprocesses. The concepts and procedures of using probing resources may beadopted and utilized in general network reconfigurations, iteratednetwork optimizations, etc.

Probing resources may include probing reference signals (P-RS) andprobing interference measurement resources (P-IMR). In LTE and LTE-A,P-RS may be considered a special CSI-RS, which may be called P-CSI-RS. AUE may not need to distinguish P-CSI-RS from other CSI-RS. P-IMR may beconsidered a special CSI-IM resource, which may be called P-CSI-IMR. AUE may not need to distinguish P-CSI-IMR from other CSI-IM resources.Any generalization or specialization or variation of the referencesignals or interference measurement resources in LTE or LTE-A may alsobe used for probing. An RRM/RLM or CSI report may be configured based onthe P-RS and P-IMR. Therefore, probing resources may be UE transparentat times. The filter state may be reset once the eNBs start or finishtesting a configuration. The reset may include both the signalmeasurements and interference measurements. The interference measurementrestart may be triggered by a reconfiguration signal to a UE. However,the signal measurement restart may be triggered by anotherreconfiguration signal. Alternatively, this reset may be doneautomatically according to a specific timing window associated with theP-RS or P-IMR or the corresponding CSI. The timing configuration may beconfigured by signaling or specifications. Alternatively, triggeringsignaling may be sent to a UE to inform the UE about the start, theintervals, and the end of the probing process. In existing standardspecifications, multiple CSI processes (CSI reporting configurations,each of which is generally associated with one signal-interferencecondition) may be supported, but only one RRM measurement process issupported. Introducing P-RS and P-IMR based RRM measurements mayintroduce multiple RRM measurement processes into the system.

In general, however, the probing resources may or may not be based onP-CSI-RS or P-CSI-IMR. The resources may be based on general P-RS andP-IMR, which may be any time/frequency RS resources and CSI-IM resourcesassigned for probing purposes. Moreover, the resources may not be basedon separate P-RS or P-IMR. Instead, the resources may be any generaltime/frequency resources usable for probing purposes. For example,CRS-like reference signals may be used for probing, and the UE may needto first detect the signals, then remove the signals to estimate theinterference on the same time/frequency resource, and finally generateCQI reports. For example, the eNBs may assign some time/frequencyresources on which some eNBs may transmit data and/or DMRS. The UE maydecode the data and/or DMRS and may measure and report CSI (e.g., CQI,PMI, RI, modulation and coding scheme (MCS) level, RSRP, RSRQ,signal-to-interference-plus-noise ratio (SINR), channel covariancematrix, interference level, interference covariance matrix, delta CQI,delta RSRP, delta RSRQ, and/or delta interference), or the UE maymeasure and report the general condition of the transmission (e.g.,acknowledgement/negative acknowledgement (ACK/NACK) or the probabilityof a decoding error). The eNBs may probe for one or more configurationsconcurrently (e.g., to use the frequency dimension to help reduceprobing duration) on multiple probing resources, and the UEs may measureand report one or more CSI. The probing resources may or may not bededicated for probing purposes only. The eNBs may instead reuse a subsetof CSI-RS and CSI-IM resources to perform probing and may reuse a subsetof CSI report configurations to report the channel status. The eNBs mayalso schedule some physical resource blocks (PRBs) to transmit dummydata, using some configurations to be probed to check the UE feedback.The eNBs may also allocate specific resources for probing and configurecertain parameters for probing (such as measurement timings and/orreporting timings) and may signal the resources and/or parameters to theUEs. The UEs may follow defined probing procedures with the signaledparameters on the specified resources, in which case the probing is notUE-transparent. The probing resources being set aside by the eNB may lieon UL time/frequency resources, in which case the probing may be done inthe uplink.

Probing resources may be used mainly for adjustment, probing, and/orprediction purposes and are not limited to the transition of a pointturning on or off. Such resources may be applied in general networkresource adaptations and transitions or in a transmission scheme change(e.g., a CoMP scheme change) in an iterative way. Such resources may beused for adjustment or fine tuning of cell association, power levels,carrier selection, carrier/point on/off decision, loadbalancing/aggregation/shifting, number of antenna ports, antennaconfigurations, bandwidth, antenna tilts, codebook structures andparameters, rank adaptation, or precoding. Such resources may be used toprovide the eNB the ability to dynamically use a different transmissionscheme based on the feedback using the probing resources. Probingresources may be configured differently for subbands to experiment atthe same time. Feedback based on probing resources may be more lightlyweighted than other feedback, e.g., lower accuracy, lower overhead,and/or with PMI/RI, etc. Measurements and feedback reports based onprobing resources may include CQI, PMI, RI, MCS level, RSRP, RSRQ,channel covariance matrix, interference level, interference covariancematrix, delta CQI, delta RSRP, delta RSRQ, and delta interference. Suchreports may also be used for UL adjustment or probing or performanceprediction. Moreover, in order for the network to be able to determinesuitable transmission schemes by probing, the network may need tosupport most or all of the transmission modes on probing resources. Forexample, the normal data transmission may be in transmission mode 8(TM8), while in the meantime the probing transmission is set to beconsistent with TM10. To determine data SINR for, e.g., TM10, byprobing, the network may configure a UE to first report CQI/PMI/RI/MCSbased on reference signal resources and interference measurementresources of the probing resources. Following the first reporting the UEreports SINR based on data (or dummy data) received on probingresources.

In E-UTRA, RSRQ is the ratio NxRSRP/(E-UTRA carrier RSSI), where N isthe number of RBs of the E-UTRA carrier RSSI measurement bandwidth. Themeasurements in the numerator and denominator are made over the same setof RBs. E-UTRA Carrier RSSI comprises the linear average of the totalreceived power (in [W]) observed only in OFDM symbols containingreference symbols for antenna port 0, in the measurement bandwidth, overN number of RBs by the UE from all sources, including co-channel servingand non-serving cells, adjacent channel interference, thermal noise etc.If higher-layer signaling indicates certain subframes for performingRSRQ measurements, then RSSI is measured over all OFDM symbols in theindicated subframes. In future releases, RSSI may be measured on certainREs specified by the eNB. In general, total received power includes allradio frequency (RF) signals received by a UE, such as the signals fromserving cells, interference, and noise, over the time/frequencyresources specified in the specifications or indicated by a networkcontroller.

FIG. 4 illustrates a timeline of operations 400 for a transitionadjustment period 402 based on probing resources, according to certainembodiments of this disclosure. In the first column 404, eNBs, e.g.,eNB1 406 and eNB2 408, set aside probing resources, and coordinateprobing transmissions and timings. In the second column 410, eNBs testprobing transmissions and adjust. In the third column 412, convergenceis achieved on probing resources. In the fourth column 414, the networkoperates per the selected reconfiguration. Further details of variousembodiments are described below.

FIG. 5 illustrates an example timeline of operations 500 for atransition decision and a transition adjustment process 502 based onprobing resources, according to certain embodiments of this disclosure.The network prepares for the transition and adapts to the transitionuntil stabilization, or experiments with different configurations tofind a desired or optimum configuration at 504. Convergence and/or thedesired behavior is achieved on the probing resources at 506, and thenetwork selects a reconfiguration and operates per the selectedreconfiguration at 508.

In various embodiments, an eNB experiencing a transition or foreseeing atransition may take the following steps. The eNB may send areconfiguration signal, together with timing information, over thebackhaul to other eNBs. The eNB may send a reconfiguration signal,together with timing information, to its UEs. The eNB may configureprobing resources, including a P-RS and a P-IMR to its UEs, and mayconfigure a transmission scheme with coordination with other eNBs on theprobing resources. The effects of the transition and reconfigurationsare iteratively evaluated and/or predicted by the network on the probingresources only. The final configuration obtained at the end of theevaluation period is then applied on all relevant resources. Therelevant resources may or may not be in the same type of carrier as thaton which the probing was done. For example, the final configurations maybe applied on a new carrier type (NCT) whereas the probing may have beendone on a Release 8 compatible carrier.

Various embodiments provide transmission, reception, and signalingmethods and systems for reconfiguration in wireless networks.Embodiments provide signals and processes supporting thereconfiguration, either after the transition or jointly with thetransition. Such signals and processes may include backhaul signaling tocoordinate the reconfiguration among multiple nodes, referenceresources, such as probing resources including P-RS and P-IMR, tomeasure the effect of transition and reconfiguration by UEs, andreconfiguration signaling to UEs to indicate the occurrence oftransition and reconfiguration to the UEs. For example, UEs may restarttheir measurement processes for the updated configurations.

In an embodiment, the impact of the transition and adaptation may beevaluated by multiple nodes and/or UEs before, during, and/or after thetransition and adaptation take place. Probing resources based on CSI-RSand interference measurements may be used to evaluate the impact of thetransition, adaptation, and/or reconfiguration before the transition,adaptation, and/or reconfiguration is applied to the PDSCH. In anembodiment, the network and UEs may adjust their configurations.Signaling from an eNB to a UE or another eNB may indicate that atransition and/or reconfiguration will occur such that the UE and othereNBs may operate accordingly. Embodiments provide reconfigurationsignals and processes when the network adapts its topology and/ortransmissions. Embodiments may be implemented in handsets and networksused in wireless communication systems.

Probing process may or may not always involve UEs. For example, asdescribed with regard to FIG. 2 , probing process may be used toreconfigure the transmissions between macros and relays over the air.Probing may or may not always involve eNB reconfigurations. For example,in a device-to-device (D2D) or direct mobile communication (DMC)network, probing may be used to reconfigure transmissions between UEs.In these cases, the general approaches having been described in variousembodiments may still be applied with appropriate modifications.

As an example, a network may experience decreased traffic load and maytry to turn off some picos to save energy or reduce emission. Thenetwork may determine some candidate picos to be turned off. However,these candidate picos may be serving UEs, and if some of the picos areactually turned off, the UEs being served by the picos may need to beoffloaded to other active picos. Such offloading may significantlychange various aspects of the network operations, such as interferenceconditions, pico/UE associations, and pico loadings. For example, if aUE is offloaded from its current serving pico to a second pico, thesecond pico may experience an increase of its loading. If the increaseof loading exceeds a threshold, QoS of the UE may suffer significantly,and hence the network may decide not to offload to the second pico ormay decide not to turn off the first pico. It may be seen from thisparticular example that the network may need to predict operationcondition before making a transition decision; otherwise, severeproblems may be caused. Such a prediction, though very useful, is verydifficult without being actually tested in the network. In thissituation, probing may be beneficial. For example, on some probingresources, a first pico “emulates” the status that it is turned off (andhence interference to neighboring points' UEs is reduced) and its UE isoffloaded to a second pico. The UE reports the CQI associated with thisprobing setting, which may help the network to determine if the decisionto turn off the first pico is eventually beneficial or problematic tothe network. A second pico may perform an actual transmission and/orscheduling of a UE on the probing resources, thus the network may obtainmuch information regarding impact of turning off a pico and offloading aUE's service.

Optionally, for DL or backhaul signaling, an eNB may send areconfiguration signal or together with a timing to UEs and other eNBs.The UE may assume that a new measurement condition, e.g. for signalmeasurements and/or interference measurements, will be in effect for anindicated CSI-RS resource configuration, CSI-IM resource configuration,and/or CSI process configuration. The eNBs may be assumed to reconfigureaccording to their UEs' feedback based on the indicated resourcesconfiguration.

Optionally, for DL or backhaul signaling, an eNB may send a signal toindicate a start and/or a finish of a transition adjustment period.Within the period, probing resources may be used to experiment withseveral configurations. A UE may apply a measurement timing windowduring the period. After each measurement timing window, the UE mayrestart its measurement process on the probing resources.

Regarding UE reconfiguration signal design, if the reconfigurationsignal is in the PDCCH or EPDCCH, the latency may be small, but downlinkcontrol information (DCI) formats may need to be modified to include thereconfiguration indications. The reconfiguration may not be logicallyrelated to DL/UL grants since it may happen that when an eNB needs totransmit a reconfiguration signal to a UE, the eNB has no DL/UL grantsfor the UE. Then a reconfiguration signal may be a field of a DCIformat, or may be a special, light-weight DCI for the reconfiguration.If the reconfiguration signal is in upper layer signaling, the latencymay be large, but there may be no need to modify DCI formats. If thereconfiguration signal is in common channels, not all UEs may need toreconfigure.

Regarding UE behavior, in general, UE layer 1 filtering design andoperation is an implementation issue not specified in thespecifications. However, the UE may be signaled if a network transitionoccurs, which may require specification support. Whether and/or how theUE reacts is generally left for implementation, which does not requirespecification support. UE layer 3 filtering for RSSI/RSRQ may need to bereset, and if so, that filtering may need to be standardized for thenetwork.

Regarding a UE's behavior, if the probing resources are mainly used forgenerating the probed CSI, the UE may need to rate matching around theprobing resources, regardless of whether the resource is used as P-RS orP-IMR, and regardless of whether the probing resources are CSI-RS/CSI-IMresources or not. However, if the probing resources carry actual data(e.g., the probing resources are used for data transmission instead ofdata for measurement), then the UE may not perform rate matching on allprobing resources. Instead, the UE may perform rate matching on a subsetof probing resources that are for measurement purposes. Appropriate ratematching signaling may be used to support such operations, such as thesignaling of zero-power CSI-RS configurations to a UE.

The probing resources may be associated with a trigger or a timingwindow to automatically restart the measurement process. RRM/CSIfeedback report configurations based on the probing resources may bedifferent from other feedback reports. Therefore, multiple timingconfigurations may be used for multiple measurement processes orconfigurations.

In an embodiment method for adaptation in a wireless network, eNBscoordinate and set aside a set of time/frequency resources for probingpurposes, eNBs coordinate a set of operations (probing transmissions)and timings to be used to synchronize actions of eNBs and UEs, eNBssignal the resources and timings to UEs, eNBs perform the coordinatedoperations on the resources according to the timings, and eNBs receivefeedback reports from UEs based on UE measurements on the signaledresources according to the signaled timings (eNBs collecting probingimpact). eNBs further coordinate the operations for further probing orapplying probing transmissions on broader time/frequency resources.

An embodiment method for adaptation in a wireless network includes thefollowing steps. eNB1 sends UE1 a configuration of a measurementprocess, a configuration of measurement resources associated with themeasurement process, a time interval associated with the measurementprocess, and a reporting configuration associated with the measurementprocess. These items as a whole may be referred to as probing-relatedconfigurations. One or more of these configurations may be combined asone configuration or included in another configuration. For example, theconfiguration of measurement resources may be included in theconfiguration of a measurement process. The measurement process may be aCSI process as defined in 3GPP Release 11, which may containconfigurations of channel and/or interference measurement resources(e.g., CSI-RS resources and CSI-IM resources). The reportingconfiguration may indicate periodic reporting (in which case theperiodicity and subframe offsets of the reporting subframes may besignaled) or aperiodic reporting (in which case the reporting triggerinformation may be signaled). The time interval specifies that themeasurement may be performed within the time interval.

Moreover, eNB1 may send signaling to UE2 to indicate probing-relatedconfigurations pertinent to UE2. The time interval sent to UE2 may begenerally the same as that sent to UE1. The other configurations sent toUE2 may or may not be the same as those sent to UE1. Not all UEs servedby eNB1 may receive such configurations.

Upon reception of the configurations, UE1 may perform a measurement inaccordance with the measurement process configuration based on theconfigured measurement resource within the configured time interval. Forexample, UE1 may perform SINR measurement based on the CSI-RS resourceand CSI-IM resource, starting from the beginning of the time intervaland ending at the end of the time interval. Then the UE may generate areport in accordance with the measurement process configuration and thereporting configuration based on the measurement.

An eNB1 may send the time interval information and/or measurementresource configuration information to eNB2. In general, the measurementresource configuration information may be associated with UE1 and/orUE2, or with part or all of the UEs receiving probing-relatedconfigurations from eNB1, but the measurement resource configurationinformation may or may not be identical to the measurement resourceconfiguration received by any UE from eNB1. In other words, eNB1 mayaggregate and/or select the measurement resource configurations sent toits UEs, and send the aggregated and/or selected measurement resourceconfigurations to eNB2. eNB1 may also send the time interval informationand/or measurement resource configuration information to eNB3. Though ingeneral the time interval information is the same, the measurementresource configuration information sent to eNB3 may or may not be thesame as that sent to eNB2. eNB2 may send probing-related configurationsto its UEs, wherein, in general, the time interval information is thesame across all UEs and all eNBs (though the network has the flexibilityto configure the time intervals differently for different eNBs and/orUEs if there is some propagation isolation, for example).

The time interval may be configured as a starting time, a time duration,and/or an ending time. The starting time may be indicated as a timeoffset (such as a certain number of subframes later than the receptionsubframe), or as a time in the future (such as a subframe within a radioframe with a certain system frame number), or by a starting timetrigger. The ending time may be indicated similarly. Alternatively, theending time may be indicated indirectly from the starting and a timeduration. There may be multiple time intervals, which may be contiguousin time. The time intervals may be indicated by a starting time usingthe above-described methods as well as a periodicity. Alternatively, theperiodicity signaling may be sent at the starting time of the first timeinterval so that the UE may obtain both the periodicity and startingtime from one signaling.

Another way of specifying multiple time intervals to a UE is based onstarting time triggers. When the UE receives a first starting timetrigger, the UE starts the measurement. When the UE receives a secondstarting time trigger, the UE understands that the first time intervalis ending and the second time interval is starting, and the UE resetsthe measurement process accordingly. With either one or multiple timeintervals, the UE generates one or more measurement reports according tothe measurement process configuration and reporting configuration. Eachreport is based on measurement over the configured measurement resourceswithin one time interval of the one or multiple time intervals. Thetiming configuration may also include one or more timing gaps duringwhich the UE does not perform measurements. The configuration of atiming gap may be combined with the above-described embodiments. A UEmay receive a set of time intervals for one type of measurement andanother set of time intervals for another type of measurement, such asdifferent time intervals for RRM and CSI measurements, or different timeintervals for signal and interference measurements.

A point may take a backhaul connection only state, a limited monitoringstate, a probing state, or an active state. In the backhaul connectiononly state, the point has completely turned off its over-the-air Tx/Rxand may only Tx/Rx signaling over its limited backhaul. In the limitedmonitoring state, the point may perform limited Rx over the air and noTx over the air, and Tx/Rx may signal over its limited backhaul. In theprobing state, the point may perform over-the-air Rx, over-the-air Tx ofreference signals, and Tx/Rx over its limited backhaul. The point mayadjust its transmission parameters (e.g., RS power) during this state.In the active state, the point may perform over-the-air Tx/Rx of dataand Tx/Rx over the possibly high-speed backhaul.

FIG. 6 illustrates state transitions 600 for a point of a network,according to certain embodiments of this disclosure. The point maytransit between a backhaul connection only state 602, a limitedmonitoring state 604, a probing state 606, and an active state 608. Apoint going through a state transition may need to signal to its UEs andneighboring points over the air or over the X2 interface, which maytrigger a transition adjustment process across multiple eNBs and UEs. Apoint here may be a cell, antenna set, frequency band/carrier,macro/pico/femto/relay, etc. In addition, a point may be transitioned toor from a completely powered-off state, and the reconfiguration andtransition adjustment process may be applied as well.

FIG. 7 is a diagram of a system 700 with a coordination entity (CE)702coordinating multiple eNBs 704, according to certain embodiments of thisdisclosure. The CE 702 may be a macro eNB or other network entity. TheSeNB 704 stands for secondary (or small cell) eNB, which may becoordinated by the CE 702 via the Xn interface, usually over a non-idealbackhaul. The SeNBs 704 may be connected via the X2 interface, usuallyover a non-ideal backhaul. The CE 702 may coordinate the on/off, carrierselection, load balancing/shifting/aggregation, and other generalinterference management and coordination operations of the SeNBs 704.UEs 706 and 708 are coupled to the SeNBs 704.

FIG. 8 shows an example of the probing operation 800 over this systemarchitecture, according to certain embodiments of this disclosure, andflowcharts are shown in FIGS. 9-11 , according to certain embodiments ofthis disclosure.

In FIGS. 9-11 , the annotations inside the parentheses indicate overwhich interface the signaling is sent. Xn indicates signaling sent overthe Xn interface, while AI indicates signaling or data sent over-the-airinterface. A flowchart for CE operation 900 is shown in FIG. 9 . In step902, the CE coordinates probing resources for a plurality of eNBs. Instep 904, the CE informs the eNBs about the probing resources. In step906, the CE coordinates one or more probing transmissions with timings.In step 908, the CE informs the eNBs about probing transmissions andtimings. In step 910, the CE receives measurement reports from one ormore eNBs. In step 912, the CE makes the adaptation decision, and instep 914, the CE informs the eNBs about the decision.

FIG. 10 shows a flowchart for eNB operation 1000, according to certainembodiments of this disclosure. In step 1002, the eNB receives probingresource allocations from the CE. In step 1004, the eNB configures UEmeasurement resources and/or processes. In step 1006, the eNB receivesprobing transmissions with timings from the CE. In step 1008, the eNBsignals measurement timings to one or more UEs. In step 1010, the eNBperforms probing transmissions on probing resources per the timings. Instep 1012, the eNB receives measurement reports from the UEs. In step1014, the eNB sends measurement reports to the CE. In step 1016, the eNBreceives the decision from the CE. In step 1018, the eNB signals data tothe UE according to the decision.

FIG. 11 shows a flowchart for UE operation 1100. In step 1102, the UEreceives measurement resources and/or configurations from the eNB,according to certain embodiments of this disclosure. In step 1104, theUE receives measurement timing signaling from the eNB. In step 1106, theUE performs measurements on assigned resources per timings. In step1108, the UE transmits measurement reports to the eNB. In step 1110, theUE receives signaling from the eNB about new configurations. In step1112, the UE receives data according to the new configurations.

The preceding description has been directed toward probing-based networkadaptation, which deals with network-wide configurations such as thetransmission scheme used in the network, transmission power levels usedin the network, the network nodes that are turned on or off, whetherCoMP or similar advanced transmission techniques are used, and similartopics. The description will now turn to probing-based link adaptation,which may be considered a special case of probing-based networkadaptation.

In a wireless network, probing may be used to determine the appropriatelink adaptation, including the MCS levels, rank, and UE pairing (formulti-user multiple-input, multiple-output (MU-MIMO), for example). Inan embodiment, in such probing-based link adaptation, a serving eNB andone or more potentially interfering eNBs transmit probing signals to aUE before transmitting actual data signals. The eNBs transmit theprobing signals at the same time and on the same time/frequencyresources. Thus, the interference the UE experiences in a probingtransmission is similar to the interference the UE will experience in anactual data transmission. The REs on which a probing signal is sent area subset of the REs that will be used for an actual data transmission.In other words, the number of REs occupied by a probing signal is lessthan the number of REs in a subframe. The UE measures the CQI or someother channel quality parameter of the probing signals and, based on themeasurement, determines an MCS level appropriate for the current channelconditions. The UE then informs the eNBs of that MCS level. The eNBsthen use that MCS when transmitting actual data to the UE. In this way,eNBs may transmit with an MCS level that is appropriate for the currentchannel conditions.

In particular, in an embodiment, multiple eNBs transmit on the sametime/frequency resources of the P-RS using a tentative MCS. Thesetransmissions may be called pre-transmissions, probing transmissions, orP-TX. UEs receiving the P-TX perform measurements on the P-RS andcalculate an updated MCS, for example. Alternatively, a CQI or otherchannel quality parameter may be derived based on the MCS. If multiplelayers are used, multiple MCSs may need to be calculated. The updatedMCS is reported to the eNBs. Alternatively, the MCS may be indicated bythe difference between the MCS and a reference MCS known to at least oneof the eNBs and the UE. The eNBs then perform the actual datatransmissions associated with the P-TX using the updated MCS. The actualdata transmissions may be called actual transmissions, post-probingtransmissions, or A-TX. Since the transmission scheme and otherparameters associated with the A-TX are the same as those associatedwith the P-TX except for the MCS, and since changes of the MCS havelittle impact on the UEs' SINR, it may be seen that the UEs experiencealmost the same SINR in the A-TX as in the P-TX. Hence, the MCSdetermined during the P-TX will match the SINR in the A-TX reasonablywell. In other words, probing may be used to significantly reduce themismatches in link adaptation. The much improved accuracy in linkadaptation may then translate to throughput performance gains.

FIG. 12 illustrates an embodiment of the probing-based link adaptationprocedure, according to certain embodiments of this disclosure. At 1202,an eNB transmits scheduling, resource allocation and correspondingprobing signals. At 1204, a UE receives the scheduling, resourceallocation and corresponding probing signals. At 1206, the UE measuresthe signal and interference and estimates an MCS level. At 1208, the UEsends a measurement report containing the estimated MCS level. At 1210,the eNB receives the measurements report. At 1212, the eNB decides on anMCS level. At 1214, the eNB transmits data based on the correspondingscheduling, resource allocation and MCS information. At 1216, the UEreceives the data transmission. Alternatively, at 1208, the UE sends anMCS level determined based on the measured signal and interference, andat 1210, the eNB receives the MCS. At 1212, the eNB decides to use thereceived MCS level, and at 1214 the eNB transmits using the received MCSlevel.

It may be noted that one probing result based on a P-TX may be appliedto more than one A-TX. In the case of multiple A-TX for a P-TX, the eNBsmay perform the scheduling and precoding in all the A-TX subframesconsistent with the P-TX. In general, the timing between resourceallocation information transmission, probing resource, probing feedback,MCS information transmission, and data transmission may take at most 4transmission time intervals (TTIs) as shown in FIG. 12 , but 3 or even 2TTIs may be sufficient if the UE may receive the P-RS early enough(e.g., using CSI-RS on 5th and 6th OFDM symbols) and process themeasurements fast enough (e.g., send report on N+1) and if the eNB mayprepare the A-TX (transmission block (TB) sizes, etc.) fast enough. Intime division duplex (IDD) systems, probing may be used similarly, butthe timing and/or latency may be different from frequency divisionduplex (FDD).

FIG. 13 shows an embodiment of probing for link adaptation, according tocertain embodiments of this disclosure. In FIG. 13 , at subframe n 1302,eNB1 1304 performs P-TX on the P-RSs (as an example, the P-RSs areCSI-RS and in particular may be non-zero-power (NZP) CSI-RS). In otherwords, eNB1 1304 transmits probing signals at the time/frequencyresources labeled precoding1, precoding2, and precoding3, which are asubset of all the time/frequency resources available in subframe n 1302.At the same time, eNB2 1306 transmits probing signals at thetime/frequency resources labeled precoding4, precoding5, and precoding6,which correspond in time and frequency to the time/frequency resourceslabeled precoding1, precoding2, and precoding3. The P-RSs transmitted byeNB1 1304 and eNB2 1306 may be precoded with RB-specific precoding. Inother words, each RB may be allowed to have a different precoding andrank, but some RBs may share the same precoding and rank (see below fordetails).

A modulation level for these P-RSs may be fixed to be quadrature phaseshift keying (QPSK) for simplicity of UE measurements, but higher ordermodulations are also allowed for higher accuracy of link adaptation. Thecoding rate may be chosen to be the lowest coding rate for theassociated modulation level, or may be a fixed at a pre-determinedcoding rate known to the UEs, or may vary dynamically. In other words,the MCS level used for the probing transmissions may or may not beoptimal for the channel conditions experienced by the UE, but theprobing transmissions may be used to determine an MCS level appropriatefor those conditions.

It is possible that more than one CSI-RS configuration may be used asthe P-RS, which may help increase the processing gains for probing.Multiple probing within one RB may also be allowed for differentprecoding vectors or matrices. P-RS may not need to span the entirebandwidth. In other words, CSI-RS on some RBs may not be used forprobing for link adaptation. The UE may treat such RBs as regular CSI-RSfor measurements.

Some UEs served by eNB1 1304 may receive signaling from eNB1 1304 aboutthe probing. Such signaling may indicate to a UE the time/frequencyresources on which the UE-specific probing is performed. For example,UE1 may be signaled that the resources associated with precoding 1 and 2are for UE1's probing. In this case, in general, precoding 1 and 2 arethe same. UE2 may be signaled that the resources associated withprecoding 3 are for UE2's probing. Likewise, some UEs served by eNB21306 may receive signaling from eNB2 1306 about the probing. UE3 may besignaled that the resources associated with precoding 4 are for UE3'sprobing. UE4 may be signaled that the resources associated withprecoding 5 and 6 are for UE4's probing. In this case, in general,precoding 5 and 6 are the same. In other words, which RBs are used forwhich UEs may be partitioned differently for different eNBs.

Then the UE may follow the eNB's instructions for measurements forprobing. The signal measurement for the UE may be obtained from allprobing resources assigned for that UE (with proper filtering). Theinterference measurements for the UE may be obtained from all probingresources for that UE, removing the effects of the signals. Then the UEmay obtain a composite SINR for all probing resources assigned for thatUE (with proper processing) and/or a composite CQI and/or MCS for allprobing resources assigned for that UE (with proper processing). Theobtained measurement result is then fed back to the eNB. If multiplemeasurement processes (e.g., CSI processes) are configured for probing,then the UE may not be allowed to mix the signal measurements fordifferent processes, and may not be allowed to mix the interferencemeasurements for different processes. However, within the sameprocesses, the signal measurements may be combined, and the interferencemeasurements may be combined according to eNB indication.

The modulation level for P-RS may be simply QPSK, which matches thegeneral RS design, and has the advantage of simple demodulation.Moreover, the modulation level of the P-RS generally does not affect theSINR of probing, from either the signal statistics or interferencestatistics points of views. However, if a more complicated receiveralgorithm is to be used, such as maximum likelihood (ML) receivers withinterference cancellation, then QPSK may not be appropriate for allprobing, and the P-TX and A-TX may use the same modulation level inorder to have accurate link adaptation.

At a later time, such as at subframe n+k 1308, the eNBs perform theA-TX. In other words, eNB1 1304 and eNB2 1306 transmit data in subframen+k 1308 in the time/frequency resources that were not used for probingtransmissions in subframe n 1302. The resource allocation for each UE isgenerally the same as that for the P-TX. In an embodiment, the timeinterval between subframe n 1302 and subframe n+k 1308 is configured ascommon for eNB1 1304 and eNB2 1306. The (new) MCS level in the A-TX foreach UE is in accordance with the UE probing feedback. For example,precoding 1 is used by eNB1 1304 for UE1 on all the RBs for UE1, and theassociated new MCS is used. Likewise, precoding 3 is used by eNB1 1304for UE2 on all the RBs for UE2, and the associated new MCS is used.Precoding 4 is used by eNB2 1306 for UE3 on all the RBs for UE3, and theassociated new MCS is used. Precoding 5 is used by eNB2 1306 for UE4 onall the RBs for UE4, and the associated new MCS is used. If, in P-TX,eNB1's precoding is transmitted together with eNB2's precoding on a RB,then it may be desirable (at least for simplicity) that in A-TX, eNB1'sprecoding is transmitted together with eNB2's precoding on the datatransmission of the RB.

Some changes in the actual scheduling from the pre-scheduling may beallowed, but it may be desirable for the changes to be made in such amanner that each UE continues to experience the same amount ofinterference. For example, the changes may be a reshuffling of thepositions of the RBs by all eNBs simultaneously, or a scaling of thenumbers of RBs for a subset of UEs by all eNBs simultaneously. Overall,as the interference at subframe n+k 1308 becomes “predictable”, accuratelink adaptation is achieved, and the transmissions to the UEs may besuccessful in one shot. A more aggressive transmission may lead todecoding failures. Rate matching and/or puncturing may be specific sothat a UE may remove the non-PDSCH REs. The rate matched REs orpunctured REs may be more than P-RS REs used by the UE. In general, ifCSI-RS is used for probing, rate matching may be based on zero power(ZP)-CSI-RS, and hence no additional rate matching signaling may beneeded. But if non-CSI-RS is used for probing, then rate matching mayneed to be specified.

P-TX signaling may be designed as follows. First, the signaling may be aDCI (e.g., physical (PHY) layer signaling carried in a PDCCH or EPDCCHin the same subframe as the P-TX). The signaling may be UE-specific orUE-group-specific. The signaling may be independent of the signaling foractual scheduling (if any) in the subframe. The signaling may indicateto a UE that one or more of the CSI-RS configurations are used forprobing (e.g., used as P-RS, which may be restricted on certain RBs,subbands, and/or resource block groups (RBGs)). The P-TX signaling maynot need to include a CSI-IMR. The number of layers and/or antenna portsmay be indicated. The signaling may indicate to a UE the RBs, subbands,RBGs, and/or virtual component carriers (CCs) on which the UE is toperform probing measurements based on the P-RS. The signaling mayindicate to a UE that averaging is not to be performed on the probingresources. The signaling may indicate to a UE the RBs, subbands, RBGs,and/or virtual CCs on which the UE is not to perform measurements basedon the P-RS. For those CSI-RS REs, regular CSI-RS based measurements maybe performed as indicated, or the UE may ignore those CSI-RS formeasurements as indicated.

If, according to certain embodiments, the UE is required to reportmeasurements for all the RBs, subbands, RBGs, and/or virtual CCs but theUE was not informed by the pre-scheduling signaling to performmeasurement on some of the RBs, subbands, RBGs, and/or virtual CCs, theUE may assume regular CSI-RS-based measurements on those resources andreport on those measurements, or the UE may report INVALID. Multipleprobing processes may be indicated. The manner in which the measurementreport is to be generated may also be indicated. The P-TX signaling mayalso include information related to the uplink, such as whether the UEshould report its measurements on the PUCCH or the PUSCH and thesubframes and/or RBs on which the UE should report its measurements. TheP-TX signaling may or may not be in the same subframe and/or samecarrier as the P-RS, In other words, a cross-subframe and/orcross-carrier pre-scheduling may be allowed. P-TX signaling thatincludes such information may be referred to as a trigger, since suchsignaling triggers the UE to perform measurements on the probingsignals. Likewise, a DCI that includes such information may be referredto as a trigger.

The UE may generate one probing measurement report based on all probingresources indicated by the signaling. In other words, a common MCSand/or SINR for all probing resources indicated by the signaling may begenerated and reported. Alternatively, multiple probing measurements forthe RBs, subbands, and/or RBGs as indicated by the signaling (or for allRBs, subbands, RBGs, and/or virtual CCs in the carrier) may begenerated. In other words, a separate MCS and/or SINR for each frequencyunit of the probing resources indicated by the signaling (or for theentire bandwidth of the carrier) may be generated and reported. Theprobing measurement report may contain less information than traditionalCQI reporting. In particular, the probing measurement report may containonly the MCS level selected by the UE based on the probing signal.

The A-TX scheduling signaling may be related to the P-TX pre-schedulingsignaling. For example, the UE may assume the resource allocations inthe two subframes are identical, unless the eNB modifies theallocations. In general, the rank, layer, port, and/or PMI (if needed tobe signaled to the UE, such as in a non-DMRS-based TM) may be the sameas the P-TX, so the signaling may not need to carry those fields.However, information such as the updated MCS or the new data indicatormay need to be signaled. Alternatively, A-TX scheduling signaling may beindependent of the P-TX pre-scheduling signaling, and the eNBs may havemore flexibility in modifying the A-TX resource allocation.

In probing-based link adaptation, multiple eNBs may transmit probingsignals at the same time and on the same frequency resources. Thus, theUE may experience interference that swamps the signal. In an embodiment,frequency unit bundling may be used to address this issue. A frequencyunit may be RBs, subbands, RBGs, or virtual CCs. The followingembodiment is illustrated on RB bundling but may apply to similarfrequency unit. In RB bundling, a few RBs (e.g., 2, 3, 5, 6, 10, 12, ormore) may be bundled as one pre-scheduling unit or scheduling unit. As aconsequence, an eNB may assign the bundled RBs to one UE, with the sameprecoding. For example, for eNB1, the P-RS on RBs 0, 1, 2 may beassigned for UE1 and one common precoding may be used on these P-RS, andthe P-RS on RBs 3, 4, 5 may be assigned for UE2 and one common precodingmay be used on these P-RS, and so on. More than one bundle of RBs may beassigned to one UE. For eNB2, the P-RS on RBs 0, 1, 2 may be assignedfor UE3 and one common precoding may be used on these P-RS, and the P-RSon RBs 3, 4, 5 may be assigned for UE4 and one common precoding may beused on these P-RS, and so on. The bundling for the eNBs may be aligned.The bundling may be known to both the eNBs and their UEs in probing. TheUE may assume the interference on each bundle be the same. For example,for each of the dominant interferers performing probing, the precodingson the P-RS in the bundle are the same. Hence, the UE may estimate theinterference e.g., interference statistics and interference covariancematrices, more accurately on the P-RS on each bundle for betterestimation of SINR, CQI, and/or MCS. Across the bundles for the UE, theUE may not be able to assume the interference be the same unless beingnotified by the eNB otherwise. The bundling may also help reducesignaling overhead for probing.

The above example is for pre-scheduling or P-TX. For A-TX, bundling mayor may not be used, and if used, the same or different bundling may beused. In any case, the eNBs may need to ensure that the interference (orat least the interference from the dominant interferers) seen by each UEis the same as in the P-TX. For example, if in P-TX, eNB1's UE1 isassigned with RBs 0, 1, and 3 with precoding x, and eNB2's RBs 0, 1, and3 have precoding A, A, and B, then in the A-TX, eNB1 may assign UE1 withRBs 0, 1, and 3 with precoding x, and eNB2 may assign precoding A, A,and B to RBs 0, 1, and 3. Alternatively, in the A-TX, eNB1 may assign aUE with RBs 0−5 with precoding x, and eNB2 may assign precoding A, A, A,A, B, and B to RBs 0˜5 respectively. The latter may benefit fromcoordination between the eNBs. In other words, the eNBs may need tocoordinate their resource allocation for the A-TX via the backhaul. Ifall eNBs keep their resource allocation from P-TX for A-TX, then nocoordination may be needed. If A-TX RB bundling is used, the eNB maynotify the UEs so that the interference estimation and channelestimation may be more accurate.

In an embodiment, the eNBs may coordinate with one another so that theeNBs transmit the probing signals in the same resources at the same timeand so that the eNBs transmit the actual data at the same time aftertransmitting the probing signals. In particular, the eNBs may need tocoordinate on the resources for probing (e.g., setting aside P-RSresources common to all eNBs). Such resources may include the P-RSperiodicity, subframe offset, P-RS locations within the subframe, and/ornumber of maximum layers for the P-RS. Also, if RB bundling is to beused, all eNBs may need to set the same bundling. In addition, if A-TXresource allocation differs from P-TX resource allocation, then resourceallocation may need to be coordinated among the eNBs. In some cases, theeNBs may act as peers and exchange coordination information amongthemselves in a distributed manner. In other cases, one of the eNBs maybe elected to act as a coordinator. In yet other cases, some otherentity in communication with the eNBs may act as a coordinator.

The use of probing may increase overhead comparing to cases withoutprobing. To help reduce the overhead for probing, some overhead may beminimized. For example, the overhead due to CRS may be minimized sinceP-RS is now used for link adaptation. The eNB may signal the legacy UEsthat a subframe is a multicast-broadcast single frequency network(MBSFN) so that CRS needs to appear on the first OFDM symbol and nowhereelse. The eNB may configure UEs with dedicated reference signal(DRS)-based measurements and not CRS-based measurements and then CRS maynot be transmitted. The eNB may deactivate a carrier for legacy UEs andtransmit DRS for new UEs. The eNB may apply fast carrier on/off, and CRSmay be transmitted only if the carrier is turned on for datatransmission. EPDCCH may be used to replace PDCCH, so that the UE doesnot need to rely on CRS. However, if EPDCCH is used, there may be adiscrepancy between the EPDCCH precoding in the A-TX and the probingprecoding in the P-TX. To resolve this issue, EPDCCH precoding may beused in the P-RS as well, or the eNB may ensure that EPDCCH for a UE istransmitted in the RB bundle for the UE. Reducing the CRS may also helpimprove probing accuracy, as CRS is not precoded and, in certainembodiments, may not be probed.

Upon receiving the P-TX from its allocated resources, a UE may calculatethe received channel quality, e.g. SINR, using the same type of receiveras for later data transmission. If there is difficulty in deriving thereceived channel quality with specific receivers, e.g. an ML receiver,due to the low density of the P-TX signal, the UE may apply parametersassociated with a minimum mean squared error-interference rejectioncombining (MMSE-IRC) receiver in the calculation. The channel qualityresults may be used for reporting probing recommendations in differentmanners. In one manner, the UE may map the channel quality results ontocertain CQI values by also taking into account the performancedifference between a data demodulation receiver and a probing MMSE-IRCreceiver. The network may then adjust the MCS in the A-TX transmissionaccordingly. In another manner, the network does initial datatransmission scheduling. After the UE obtains the channel qualityestimation from P-TX transmission, the results are compared with thescheduled transmission conditions. The UE may report to the network theUE's recommended MCS adjustment, e.g., +1 or −1 from the initialscheduled value.

To configure the P-TX transmission, if there are UEs supportingdifferent numbers of layers in the network, the network may need to makesure that the configuration may accommodate the maximum possible layersin A-TX transmission. As an example, two UEs served by two eNBs,supporting 2 and 4 layers of data transmission, are active in the systemand are pre-scheduled on the same RBs of the two eNBs of the samesubframe. The network may configure 4-port CSI-RS resources fortransmitting P-TX to the UE targeting 4-layer data transmission andconfigure two 2-port CSI-RS resources for transmitting P-TX to the UEtargeting 2-layer data transmission. The 2-port CSI-RS resources maycompletely overlap with the 4-port CSI-RS resources. P-TX signaltransmitted in these two 2-port CSI-RS resources may be different butmay still have the same precoding or may simply be repeated. In theformer case, the UE may or may not need to know the second 2-port CSI-RSresources for probing, but the UE may need to know the second 2-portCSI-RS resources for rate matching. In the latter case, the UE with thetwo 2-port CSI-RS resources may assume identical signals and precodingare used across the two 2-port CSI-RS resources (if signaled orspecified). However, the P-RS on the same subframe of an eNB may havedifferent maximum possible layers in different RBs (or RB bundles,etc.), as long as the P-RS on the same RB across neighboring eNBs havecompletely overlapping P-RS resources.

Besides a UE reporting recommended CQI or MCS adjustment values, the UEmay also be configured to report a recommended transmission rank.Typically, rank is scheduled before the transmission of P-TX and remainsthe same during P-TX and A-TX. After the processing of P-TX, the UE mayfind favorable or unfavorable channel conditions for an upcoming A-TX ifthe same rank is maintained, but the UE may also report to the networkits favorite rank. The reported rank may be higher or lower than theoriginal scheduled rank. The rank reporting format may be an absoluterank with an index or an offset from a scheduled rank. For example, a UEmay be scheduled for rank 2 transmission and upon deriving the channelquality from P-TX, the UE may report to the network suggesting that theUE prefers rank 1 transmission in the second layer. The network may ormay not follow the UE's suggested rank for the transmission of A-TX. Ifthe network does follow the UE's suggestion and changes the rank, somecoordination may be needed between the transmitting eNBs.

With the probing signal, the UE has a much better estimation on theactual interference experienced in the data transmission. Therefore, theUE may target a smaller block error rate than normal CSI reporting,which may target average channel and interference conditions, e.g., 2%vs. 10%. In the testing of UE reporting accuracy, a legacy testingmethodology and metric may be reused.

Probing-based link adaptation may be applied to a number of scenarios.For example, such adaptation may be used for current LTE systems, withpre-coordination of the probing resources and bundling, with P-TXsignaling, and with additional operations to ensure that the A-TX andP-TX are consistent. To help overcome the issue of fewer resources forP-RS interference estimation, RB bundling of a sufficient number of RBsmay be used, which implies that probing may be especially effective in awideband system (e.g., hundreds of RBs within one carrier, which may bethe case for C-band, mmWave bands, etc.). The large RB bundle alsoimplies that fewer UEs may be multiplexed in a subframe, but thislimitation may not be a problem for a wideband system, especially formmWave systems, which may have only a few UEs multiplexed. A system withshorter TTI is also more suitable for probing as the delay caused byprobing may be reduced. Probing may also be used effectively forwireless backhaul transmissions for similar reasons. Furthermore,probing may significantly help MU-MIMO transmissions, as the paired UEsmay estimate their CQI, SINR, and/or MCS more accurately after thepairing. To this aim, the eNB may pair UEs on the common P-RS resourceson the P-TX, with precodings to the UEs and with tentative MCS levelsfor the UEs. Then the UEs may be signaled with their associatedsequences, layers, and/or ports and paired layer information (in thecase of non-transparent MU-MIMO) and may obtain their probing results.Then the eNB may transmit in the A-TX to the paired UEs with MCS levelsupdated based on probing. In MU-MIMO probing, the paired UEs in P-TX andA-TX may be consistent. Similarly, probing may be useful for CoMP, andthe P-RS signals and their precoding may be from different (virtual)cells.

Probing configuration and configuration signaling from the eNB to the UEmay include a number of items. Measurement process configuration mayinclude, for example, a number of regular and/or probing processes andtheir IDs, antenna ports for the regular and/or probing processes,and/or layers for the regular and/or probing processes. Probing resourceconfiguration may include, for example, P-RS periodicity (which may notbe present for aperiodic probing), P-RS subframe offset (which may notbe present for aperiodic probing), P-RS RE locations, CSI-RSconfigurations, antenna ports for the probing processes, and/or layersfor the probing processes. Probing signal configuration may include, forexample, sequences for serving cells, sequences for interfering cells,layers and/or ports of the serving cell signals and interfering cellsignals, and/or MCS levels for the layers and/or ports of the servingcell signals and interfering cell signals. Probing triggeringconfiguration may be based on, for example, pre-scheduling signaling,the associated DCI information, radio network temporary identifier(RNTI), resource allocation types, and/or resource allocationgranularity. Probing measurement configuration may include, for example,signal measurement and interference measurement restrictions in time,frequency, antenna ports, and/or layers, including bundling if any.Reporting configuration may include, for example, periodic reporting viaPUCCH, aperiodic reporting via PUSCH with associated time/frequencyresources, and/or reporting of one or more of MCS, CQI, SINR,recommended RI, bit error rate (BER), block error rate (BLER), frameerror rate (FER), log-likelihood ratio (LLR), ACK/NACK, delta MCS, deltaCQI, delta SINR, delta rank, etc., for each frequency unit and/or forall specified resources, for each layer. Configuration of possibleassociation of the P-TX and A-TX may include, for example, subframeoffset between the P-TX and A-TX, P-TX and A-TX on the same CC or ondifferent CCs (for carrier switching), resource allocation relationbetween the P-TX and A-TX, and/or quasi-co-location relation between theantenna ports of the P-TX and A-TX.

Embodiments of the probing process may help significantly simplifyretransmission and hybrid automatic repeat request (HARQ) functions,since the first transmission will often occur successfully. For example,the DCI may be changed such that the New Data Indicator is by default“new data” or is even removed, and the New Data Indicator may beindicated only in rare event that retransmission is needed. The HARQprocess ID may be treated similarly. UE soft buffer management may alsobe simplified to deal with essentially no retransmission. ComplicatedHARQ timing may not need to be maintained, especially for TDD systems.

3GPP recently completed a study involving elevatedbeamforming/full-dimensional MIMO (EBF/FD-MIMO). The study proposed toutilize the elevation dimension to improve the quality of service forcellular users in urban and/or dense deployment scenarios. One of thefeatures suggested in the study is a beamformed CSI-RS. Benefits ofusing beamformed reference signals include better support of EBF/FD-MIMOwith more antenna ports and improved signal estimation quality owing tobeamforming gains.

FIG. 14 illustrates an embodiment procedure 1400 for beamforming ofreference signals, according to certain embodiments of this disclosure.At event 1402, UE1 and eNB1 establish a radio resource control (RRC)connection, and at event 1404, UE2 and eNB2 establish an RRC connection.At event 1406, eNB1 and eNB2 jointly decide beamforming reference signalconfigurations common to both eNBs, such as periodicity and which REsare present in which subframes. The circled numerals in FIG. 14 indicatesteps for which more details will be provided in FIG. 15 . At event1408, eNB1 configures beamforming reference signals for UE1, and atevent 1410, eNB2 configures beamforming reference signals for UE2. Atevent 1412, eNB1 configures beamforming reference signal measurementreporting for UE1, and at event 1414, eNB2 configures beamformingreference signal measurement reporting for UE2. At event 1416, eNB1decides on probing resources and a precoding vector (v1) on thebeamforming reference signal, and at event 1418, eNB2 decides on probingresources and a precoding vector (v2) on the beamforming referencesignal. At event 1420, eNB1 transmits the beamforming reference signalon the decided probing resources and transmits pre-scheduling signalingto UE1, and at event 1422, eNB2 transmits the beamforming referencesignal on the decided probing resources and transmits pre-schedulingsignaling to UE2. Events 1420 and 1422 may occur at the same time. Atevent 1424, UE1 performs CSI measurements on the signaled resources, andat event 1426, UE2 performs CSI measurements on the signaled resources.At event 1428, UE1 reports an MCS adjustment to eNB1, and at event 1430,UE2 reports an MCS adjustment to eNB2. At event 1432, eNB1 transmitsscheduling DCI and a beamforming PDSCH with the precoding vector v1 andthe adjusted MCS to UE1, and at event 1434, eNB2 transmits schedulingDCI and a beamforming PDSCH with the precoding vector v2 and theadjusted MCS to UE2. Events 1432 and 1434 may occur at the same time.

FIG. 15 provides an embodiment of more details regarding the embodimentprocedure 1400 for beamforming of reference signals that was illustratedin FIG. 14 , according to certain embodiments of this disclosure. Block1502 provides details regarding event 1406 in FIG. 14 , where eNB1 andeNB2 jointly decide beamforming reference signal configurations commonto both eNBs. At that event, eNB1 sends eNB2 a beamforming referencesignal configuration request that may include a periodicity, such as 5ms, a subframe offset with respect to, for example, a PSS subframe orsubframe 0, and RE resources. eNB2 then accepts the request, declinesthe request, or requests a different configuration. Block 1504 providesdetails regarding event 1410 in FIG. 14 , where eNB2 configuresbeamforming reference signals for UE2. The configuration may include theperiodicity, the subframe offset, the RE resources, an associatedphysical cell ID/virtual cell ID (PCID/VCID), a power offset, areference signal MCS, and rate matching information. Block 1506 providesdetails regarding event 1414 in FIG. 14 , where eNB2 configuresbeamforming reference signal measurement reporting. The reporting may beperiodic reporting, aperiodic reporting based on a probing trigger,subband reporting, and/or wideband reporting. The configuration mayspecify report content, such as CSI, MCS, MCS adjustment, and/or RI. Theconfiguration may also specify collision handling procedures. Block 1508provides details regarding event 1430 in FIG. 14 , where UE2 reports anMCS adjustment to eNB2. At that event, UE2 may indicate the MCS level orthe CQI (without PMI and with or without RI) or an MCS adjustment withrespect to a probing MCS, such as a fixed MCS or an MCS indicated in aprobing trigger. Block 1510 provides details regarding event 1434 inFIG. 14 , where eNB2 transmits scheduling DCI and a beamforming PDSCHwith the precoding vector v2 and the adjusted MCS to UE2. At that event,eNB2 transmits DCI to schedule a PDSCH by a PDCCH or by an EPDCCH. eNB2may beamform the EPDCCH DMRS and EPDCCH REs with the precoding vectorv2. The CCE aggregation level may be determined by a probed CQI/MCS.eNB2 then transmits the PDSCH and its DMRS with the precoding vector v2.The MCS level of the PDSCH is determined by the probed CQI/MCS. ThePDSCH/EPDSCH RBs correspond to the probing RBs on which the probed MCS(e.g., the beamforming reference signal measurement report) is based.For example, if in probing, beamforming reference signals weretransmitted on RBs 5 and 8, and UE2 performed measurements and reportedthe CQI/MCS based on RBs 5 and 8, then eNB2 may do PDSCH scheduling onRBs 5 and 8 for UE2.

A CSI process may be configured with class A CSI reporting, class B CSIreporting, or both. In Class A, a UE reports CSI according to W=W1W2codebook based on {[8],12,16} CSI-RS ports; this is basically the legacybehavior. In Class B, a UE may report L-port CSI, based on, e.g., anindicator for beam selection and L-port CQI/PMI/RI for the selectedbeam, where the total configured number of ports across all CSI-RSresources in the CSI process is larger than L. Alternatively, the UE mayreport L-port precoder from a codebook reflecting both beam selectionand co-phasing across two polarizations jointly, where the totalconfigured number of ports in the CSI process is L. Alternatively, theUE may report a codebook reflecting beam selection and L-port CSI forthe selected beam, where the total configured number of ports across allCSI-RS resources in the CSI process is larger than L. Alternatively, theUE may report L-port CQI/PMI/RI, where the total configured number ofports in the CSI process is L.

Beam selection by a UE constitutes either a selection of a subset ofantenna ports within a single CSI-RS resource or a selection of a CSI-RSresource from a set of resources. When a beam is selected and the indexassociated with the beam is sent by the UE, this may be referred to asbeam index (BI) reporting. However, as the beam actually corresponds toa particular CSI-RS resource (or resource configuration), what is seenand selected by the UE is just the CSI-RS resource (or resourceconfiguration) associated with the beam. For this reason, BI may also bereferred to as CSI resource indicator (CRI) or the like.

Measurement restrictions for signal/channel measurements andinterference measurements (IM) and methods for performing interferencemeasurements in FD-MIMO will now be described.

Using interference measurement as an example, different CSI-IM REs (intime and/or frequency, or REs used for interference measurements) mayexperience different precoding weights. This is especially so as theprecoding weights may be UE-specific and vary in time/frequency. Aninterference measurement based on time-domain and/or frequency-domaininterpolation and/or averaging corresponding to different precodingweights may not have any clear physical meaning. A similar issue existsin signal/channel measurement. The eNB may change its beamforming in thetime/frequency domains, for different UEs, for UE mobility support, foradaptation of vertical sectors (which may be a special form of virtualsectors, formed by different ways of eNB 2D antenna arrayanalog/digital/hybrid beamforming/steering), etc. Therefore, measurementrestriction (MR) may need to be applied in the time and/or frequencydomains (independently or dependently), and for signal/channelmeasurements and interference measurements (independently ordependently).

For a given CSI process, if MR on channel measurement is ON, then thechannel used for CSI computation may be estimated from X NZP CSI-RSsubframes up to and including a CSI reference resource. Channelmeasurement is derived from NZP CSI-RS. MR may be based on Li triggeringand/or higher-layer signaling for a dynamic CSI request. For a given CSIprocess with CSI-IM, if MR on interference measurement is ON, then theinterference used for CSI computation may be estimated from Y CSI-IMsubframes up to and including a CSI reference resource. Interferencemeasurement is derived from CSI-IM. MR may be based on Li triggeringand/or higher-layer signaling for a dynamic CSI request. If a CSIprocess may be configured without CSI-IM, for a given CSI processwithout CSI-IM, if MR on interference measurement is ON, theninterference used for CSI computation may be estimated from V subframesup to and including a CSI reference resource.

In a first alternative (Alt1), fixed MR is turned ON or OFF viahigher-layer configuration, and X and Y are each fixed to a singlevalue.

In a second alternative (Alt2), configurable MR is turned ON or OFF viahigher-layer configuration, and X={OFF, 1, . . . , NX} are higher-layerconfigurable and Y={OFF, 1, . . . , NY} are higher-layer configurable.

In a third alternative (Alt3), CSI measurement is periodically reset,where a reset period and a subframe offset are higher-layer configured.X is selected by the UE between 1 and ZX where ZX is the number ofCSI-RS subframes between the latest measurement reset and the CSIreference resource. Y is selected by the UE between 1 and ZY where ZY isthe number of CSI-IM subframes between the latest measurement reset andthe CSI reference resource.

In the above descriptions, X is the number of CSI-RS subframes used fora UE to perform signal/channel measurement averaging/filtering, and Y isthe number of subframes used for a UE to perform interferencemeasurement averaging/filtering. If CSI-RS REs are used for IM, thesubframes are CSI-RS subframes. If CSI-IM resources are used for IM, thesubframes are CSI-IM resource subframes. If CRS REs are used for IM, thesubframes are CRS-bearing subframes.

A CSI process is associated with K CSI-RS resources/configurations e.g.per definition in 3GPP TS 36.211, with Nk ports for the kth CSI-RSresource (K could be >=1). For class A and class B and all values of K,MR is independently configurable for each subframe set, when legacymeasurement restrictions with two subframe sets are also configured in aCSI process. One RRC parameter for channel measurement (for class B) andone RRC parameter for interference measurement (for classes A and B) areprovided to enable or disable MR. MR may apply to both periodic andaperiodic CSI reporting or only to aperiodic reporting (e.g., with MRnever enabled for periodic reporting). For class A and class B with K=1,Alt1 (with X=Y=1) is supported. For class B with K>1, Alt1 (with X=Y=1)or Alt3 may be implemented, with the understanding that existing RRCparameters (e.g., the reset period is equal to the BI period and theoffset is fixed) may be reused for Alt3, and consideration of aperiodicreset is also not precluded.

Alt3, where CSI measurement is periodically or aperiodically reset, isnow described in more detail.

FIG. 16 illustrates an example 1600 of Alt3 from the point of view of aUE, according to certain embodiments of this disclosure. Signalmeasurement is shown in the figure, but interference measurement may bedone similarly. For simplicity, most of the descriptions assume themeasurement reset is performed periodically and according to the BIperiod and reporting. However, the procedures may be easily generalizedto cases with aperiodic reset and/or according to some triggeringsignaling (which may be independent for signal/channel measurement andinterference measurement).

A BI period 1602 starts on the subframe 1604 where the UE reports BI1and ends on the subframe 1606 where the UE reports BI2. The UE mayreceive the BI periodicity (or duration, together with subframe offset)information indicated at the subframes 1604 and 1606 where the UEreports BIs. The UE assumes the CSI measurement reset period is equal tothe BI period 1602, with potentially an offset 1608 with respect to theBI reporting subframe 1604. The offset 1608 may be specified. A resetperiod 1610 may be equal to the BI period 1602. The new BI (e.g., BI1)starts to be applied in DL transmission/reception on a subframe 1612later than the BI1 reporting, and the UE resets its CSI measurementprocess on this subframe 1612. The UE selects a value X 1614 between 1and Zx 1616, where Zx 1616 is the number of CSI-RS subframes between themeasurement reset subframe 1612 and the reference resource 1618. Two CSIreporting instances 1620 and 1622 are shown. For the first instance1620, Zx 1616 is smaller, whereas Zx 1616 is larger for the secondinstance 1622. The same X value 1614 or different X values 1614 may beselected by the UE. BI2 may be applied in DL transmission/reception on asubframe 1624 later than the BI2 reporting.

The benefits of Alt3 include better measurement accuracy, as moreaveraging is applied to the measurement process of the samecharacteristic. For example, in a network with time-invariantbeamforming (as opposed to time-varying beamforming) within each BIperiod, the UE may perform averaging across the subframes within each BIperiod, and this may lead to higher measurement accuracy.

The value of X may not need to be specified. From the UE's perspective,the UE may only need to know when the reset will be performed and wherethe reference resources are located. Based on these values, the UE knowsZx, and the UE may flexibly select X accordingly and autonomously. The Xvalue may be same or different for respective Zx, and may be same ordifferent for respective reset period, etc. In addition, the UEfiltering behavior may resemble the legacy filtering behavior (which hasno measurement restriction) except for an occasional measurement reset.Therefore, the manner in which filtering is done is a UE implementationissue. In other words, no mention of X is needed and it may besufficient that the UE may reset its measurement process according tothe reset timings. This also helps minimize impact.

A UE may support at least three types of behavior.

An example of a first behavior involves Alt1 (with X=Y=1), wherein themeasurement is restricted based on only one subframe. This alternativeis suitable for cases with dynamic beamforming or cases where the UE maynot have sufficient knowledge about how or when the serving orinterfering eNB beamforming is changing. This alternative provides thehighest flexibility for the network to adapt the beamforming while notconsiderably increasing the signaling overhead.

An example of a second behavior involves Alt3 (measurement reset),wherein the measurement process is reset according to a networkindication or triggering, for example by BI reporting. This alternativeis suitable for cases with semi-static beamforming or cases where the UEhas sufficient knowledge about the subframes on which the beamformingremains constant or cases where longer-term measurement is useful (e.g.,in interference measurement for some BI reporting). This alternative mayoffer higher measurement accuracy than Alt1.

An example of a third behavior, there is no measurement restriction(e.g., the legacy measurement behavior). This is already supported andused for legacy measurements, such as CSI based on non-precoded CSI-RS.

It may be preferable for Alt1 (e.g., one subframe measurementrestriction (i.e., with X=Y=1)) to be supported. Alt3 may also beconsidered in order to provide more options to the network/UEoperations, which may strike different tradeoffs between flexibility tochanging beamforming and measurement accuracy.

To conclude, a UE may support Alt1 (with X=Y=1) and Alt3 (measurementreset) for Class B with K>1. For Alt3 (measurement reset), only thereset event and instant may need to be specified, e.g., BI reporting,and other parameters may be left for UE implementation.

The reset may be tied with the BI reporting, with potentially an offset.The BI reporting may be periodic or aperiodic. In the aperiodic case,the BI reporting may be triggered by signaling in the PHY layer.Signaling may be used for BI reporting triggering only, or BI+RI (asboth are long-term measurements), or BI+RI+CQI (there may not be a PMIassociated with the CSI process), or BI+RI+CQI+PMI. The trigger mayspecify which measurement quantities are reported and which measurementquantities correspond to which BI (old BI or new BI) and/or RI.Alternatively, the trigger may merely specify which CSI processes shouldbe reported, and the associated reporting quantities may be configuredvia RRC. Alternatively, the triggering signaling may not be a newsignaling, and the existing aperiodic trigger for RI may be reusedinstead if reporting class B is configured. Alternatively, the reset maybe tied to RI reporting, BI and RI reporting, a new triggering signalingnot related to BI reporting but used for signal/interference resetpurposes, or a combination of these options. The network may configureand support these operations.

The resets for signal measurement and interference measurement may betriggered by the same event or signaling, such as BI reporting. In thiscase, the eNBs may coordinate their adaptation of the beamforming on theCSI-RS and/or data (or other adaptation such as on/off) so that the eNBsadapt at the same time. If such triggering is regarded as restrictive,separate reset triggers may be used for signal measurement and IM. Forexample, a UE may be in a sector with an interfering sector changing itsprecoding every 80 subframes, and the UE's serving sector may bechanging its precoding every 240 subframes. In such a case, the signalmeasurement may reset every 240 ms, but the IM may need to reset every80 ms. In other words, it is possible that whenever a dominantinterferer adapts its transmissions and causes a different interferencecondition, signaling may be sent from the serving sector to the UE forIM reset.

Between BI reporting and BI application (e.g., the UE measurement resetinstant), there may be an offset measured as a number of subframes. Thisoffset is likely to be four subframes, as the eNB may take about foursubframes to process and prepare to switch and also considering thetiming difference between UL and DL. Alternatively, the offset may besignaled to the UE, such as in RRC signaling for MR configuration, or inthe Li trigger.

If CSI or part of the CSI is triggered to be reported with BI,especially in the K>1 cases, there may not be sufficient time for the UEto generate the CSI measurement results associated with the new BI. Onetechnique that may be adopted to address this issue is to allow a longerlatency for BI reporting after the triggering. In other words, the UEmay wait until after the reset (e.g., BI reporting time+reset offset)and then report CSI associated with the new BI. Another technique thatmay be adopted to address this issue is for the UE to report CSIassociated with the old BI instead of the new one. In other words,before the reset, the UE may still base its CSI calculation andreporting on the old BI. For periodic reporting of BI, this issue may beless important, so the UE may be capable of reporting CSI associatedwith the new BI. However, in order to decrease UE complexity, it may bestill desirable to report CSI associated with the old BI until thereset.

Interference measurement will now be considered. Interferencemeasurement approaches include interference measurements with CSI-IMresources (also known as IMR) and interference measurements withoutCSI-IM resources.

For interference measurements with CSI-IM configured, there may be oneor more CSI processes (e.g., CoMP) for a UE, and each CSI process may beconfigured with CSI-RS and CSI-IM. The associated transmission mode maybe TM10 or its further evolution. A CSI process may be associated withone or more CSI-RSs and one or more CSI-IMs. For simplicity, thedescription may be mainly directed toward one CSI-RS/CSI-IM per CSIprocess, and it may apply similarly to cases with multiple CSI-RS/CSI-IMper CSI process. There are two cases when CSI-IM is configured,including the CSI-IM is covered and is not covered by ZP CSI-RSresources of adjacent eNBs and/or virtual sectors.

FIG. 17 illustrates an example of resources 1700 for CSI measurements ina case where CSI-IM is not covered by ZP CSI-RS resources of adjacenteNBs, according to certain embodiments of this disclosure. For such acase, adjacent eNBs do not configure ZP CSI-RS on the time/frequencyresources corresponding to the UE's CSI-IM, and no eNB coordination onCSI-IM REs may be appropriate.

The interference perceived on CSI-IM REs by the UE may be generally thesame as the interference being perceived on non-CSI-IM REs. Suchinterference reflects the current interference being experienced by theUE and might not reflect prospective interference the UE may beexperiencing; especially if the interfering cells or virtual sectors arechanging their beamforming and when the interference measurement is usedfor link adaptation in later subframes.

In FIG. 17 , there are 16 CSI-RS REs per eNB, in other words, 4 REs forsignal, 8 REs for muting of adjacent eNB signals, and 4 REs for CSI-IM.In the case of virtual sectors (e.g., each ‘eNB’ is actually a virtualsector, and the virtual sectors are actually controlled by the sameeNB), a UE may need to be configured with all the CSI-RS/CSI-IM and mayperform rate matching around them, which amounts to 24 REs in total.

FIG. 18 illustrates an example of resources 1800 for CSI measurements ina case where CSI-IM is covered by ZP CSI-RS resources of adjacent eNBs,according to certain embodiments of this disclosure. In particular, theCSI-IM of eNB0 1802 overlaps with the ZP CSI-RS of eNB1 1804 and eNB21806. The interference measured by eNB0's UE on the CSI-IM is what eNB11804 and eNB2 1806 transmit on those ZP CSI-RS, which may not be thesame as the PDSCH transmissions from eNB1 1804 and eNB2 1806 and whichmay generally need to be rate matched by UEs associated with eNB1 1804and eNB2 1806.

For the case illustrated in FIG. 18 , adjacent eNBs may need toconfigure zero-power CSI-RS on the time/frequency resourcescorresponding to a UE's CSI-IM, and their transmissions on thoseresources may need to be consistent with the coordinated transmissionhypotheses. As a result, those ZP CSI-RS resources may not be used fordata transmissions by the adjacent eNBs (e.g., rate matching may beneeded).

It may be noted that ZP CSI-RS does not may or may not be muting. If itis assumed that the CSI-IM of eNB1 1804 is covered by the ZP CSI-RS ofeNB0 1802 and further assumed that eNB0 1802 serves UE0 and eNB1 1804serves UE1, then from UE0's perspective, UE0 just performs rate matchingaround the ZP CSI-RS REs. Then eNB0 1802 may mute or transmit signalsaccording to a coordinated hypothesis on the ZP CSI-RS REs, and in thelatter case, the signals transmitted by eNB0 1802 are seen by UE1 asinterference on the CSI-IM. Therefore, ZP CSI-RS here is a mechanism forproviding the eNBs the flexible capability of measuring interferenceaccording to a certain transmission hypothesis.

The interference perceived on CSI-IM by the UE may not be directlyrelated to the interference perceived on non-CSI-IM REs (e.g., dataREs). Depending on how the eNB coordination is done, such interferencemay reflect the prospective interference the UE will experience. Inother words, on an adjacent eNB's ZP CSI-RS, the transmissions may occuraccording to a transmission hypothesis determined by the network, andthe hypothesis may be applied to actual transmissions several subframeslater.

In FIG. 18 , there are 24 CSI-RS REs, per eNB, in other words, 4 REs forsignal, 8 REs for muting of adjacent eNB signals, 8 REs fortransmissions for an adjacent cell UE's interference measurements, and 4REs for CSI-IM. A UE may need to perform rate matching around at leastthese 24 REs.

Evolution of TM10 (or potentially a new transmission mode) and/orCSI-IM-based interference measurements may be needed in Release 13 toefficiently support FD-MIMO. In addition, the following enhancement,namely, measurement restriction, may be considered.

If CSI-IM is to be used for a UE operating in EBF/FD-MIMO and the CSI-IMis covered by an adjacent eNB's ZP CSI-RS, different CSI-IM REs (in timeand/or frequency) may experience different precoding weights. This isespecially so as the precoding weights may be UE-specific and may varyin time/frequency. The interference measurement based on time-domainand/or frequency-domain interpolation and/or averaging corresponding todifferent precoding weights may not have any clear physical meaning.Therefore, measurement restriction may need to be applied in the timeand/or frequency domains. However, if the CSI-IM is not covered by anadjacent eNB's ZP CSI-RS, which is generally associated with no eNBcoordination, measurement restriction may not be applicable. Therefore,measurement restriction for interference measurements may be morerelevant if the CSI-IM is covered by an adjacent eNB's ZP CSI-RS than ifnot.

In another approach, interference measurements may not have CSI-IMconfigured. This approach is applicable to any non-CoMP scenarios, whichmay be the typical scenarios for FD-MIMO. For this approach, the CSIprocess is configured with no CSI-IM, and the associated transmissionmode may be any other than TM10, such as TM9 or its extension. (3GPP TS36.213 V12.7.0 R12 (2015-9), which is hereby incorporated herein byreference as if reproduced in full, states in Clause 70.2.1 that, “For agiven serving cell, if the UE is configured in transmission modes 1-9,the “CSI process” in Table 70.2.1-1B and Table 7.2.1-1C refers to theaperiodic CSI configured for the UE on the given serving cell.”Therefore, TMs 1-9 may be viewed to also have the concept “CSIprocesses” defined.) The interference measurements may be performed onCSI-RS REs or CRS REs. Performing the interference measurements onCSI-RS REs may be preferred. The following description assumes theinterference measurements are done on CSI-RS REs.

FIG. 19 illustrates CSI measurements 1900 without CSI-IM and withoverlapping CSI-RS, according to certain embodiments of this disclosure.A UE first detects the signal on the CSI-RS REs then subtracts thatsignal from the total received signal to obtain an interferenceestimate. More steps for interference measurements are involved in thiscase than with CSI-IM; however, such a capability may already besupported by the UE for CRS-based interference measurements. For thisexample case, the overhead is four REs (for CSI-RS) per eNB, and the UEperforms rate matching around these four REs.

In other words, in an embodiment, a plurality of eNBs transmit referencesignals on overlapping REs. In particular, a plurality of eNBs transmitthe probing reference signal or P-RS described herein on REs specifiedfor use for NZP CSI-RS. Since the reference signals overlap, a UE mayperform measurements of both signal and interference on the sameresources. Such a scheme may use less overhead than if separate REs areused for signal and interference and may also improve measurementaccuracy. Overlapping transmissions from the eNBs may be distinguishedfrom one another by having different scrambling IDs or scramblingsequences.

It is also possible to allow the CSI-RSs to be non-overlapped for theeNBs, but such an approach might not bring any benefit and might captureonly the current interference instead of potential future interference(as the precoding weights on the CSI-RSs of an adjacent eNB may be usedin later transmissions by the adjacent eNB; hence the precoding weightsmay be able to reflect potential future interference).

This approach may also allow the CSI process to have multiple CSI-RSs.The interference measurement resources for each CSI-RS are the CSI-RSREs.

It may be thought that the accuracy of interference measurement withoutCSI-IM may be reduced, mainly due to the need to first estimate andsubtract CSI-RS signals (without RE muting) before obtaining theinterference estimate. However, analysis may reveal that the measurementaccuracy is not an issue.

First, RE muting, when introduced, was primarily applied to measurementsof weak signals in CoMP. RE muting is generally not necessary fornon-CoMP as the signals are typically sufficiently strong. Second,taking the above example, the number of REs used in interferencemeasurement may be compared to the number of REs when demodulation usingDMRS is performed. In the DMRS case, there are 12 REs per RB. In theabove example, there are 4 REs per RB. However, with properinterpolation/averaging and measurement restriction (e.g., 3 or 6 RBsper feedback granularity), generally the CSI-RS REs from multiple RBsmay be used. In this way, the accuracy of CSI-RS measurements may atleast match the accuracy appropriate for demodulation, althoughsufficient measurement accuracy may be achieved at the cost of moreoperations in interference measurements. Additionally, the accuracymight be increased further due to beamforming gain since CSI-RS areprecoded in EBF/FD-MIMO. Therefore, the measurement accuracy withoutCSI-IM may not be a concern.

Similar to CSI-IM-based interference measurements, it may also beimportant to introduce proper measurement restriction in thetime/frequency domain for non-CSI-IM-based interference measurements.Therefore, CSI-RS REs may be used for interference measurements withsufficient measurement accuracy, and the interference measurementsperformed on CSI-RS REs may be enhanced by measurement restriction.

Table 1 compares the three interference measurement mechanisms describedabove.

TABLE 1 Require IM Measured Over- coordi- Require resource interferencehead nation MR A: CSI-IM not CSI-IM Present Medium/ No Not covered byREs interference high applicable adjacent eNB's ZP CSI-RS B: CSI-IMCSI-IM Prospective High Yes Yes covered by REs interference adjacenteNB's ZP CSI-RS C: No CSI-IM CSI-RS Prospective Low No Yes REsinterference

It may be seen that, in certain scenarios, mechanism C may be a suitablechoice for FD-MIMO, although this disclosure contemplates using othermechanisms if appropriate.

It may be noted that mechanism B may cover mechanism C if the CSI-IM isallowed to overlap with the CSI-RS, with proper UE behavior clarified.More specifically, the following potentially unifying solution may beadopted.

First, the UE is configured with a NZP CSI-RS. The UE may be furtherconfigured with a CSI-IM that overlaps with the CSI-RS (for, e.g., TM10or its evolution), or with no CSI-IM (for, e.g., TM9 or its evolution).Second, the UE performs signal/channel measurements based on the NZPCSI-RS. Third, the UE cancels NZP CSI-RS on the NZP CSI-RS REs, suchthat only interference is left on those REs. Fourth, the UE performsinterference measurements on those REs.

Therefore, by allowing interference measurement on the NZP CSI-RS REsand adopting the above UE behavior, the benefits associated withmechanism C may also be achieved by mechanism B. In such a case, the UEbehavior in mechanisms B and C becomes the same, which may simplify thestandardization effort. If multiple NZP CSI-RS are configured onoverlapped REs (for example, for multiple virtual sectors), then the UEmay need to perform the second and third steps above for each NZPCSI-RS. For example, if the UE is configured with three NZP CSI-RSassociated with three different virtual sectors on the same REs, the UEmay detect each of the three NZP CSI-RS for signal/channel measurementsand obtain three transmissions, S1, S2, and S3 (pre- or post-receivercombining). Then the UE subtracts the first NZP CSI-RS signal from thereceived signal on the REs, obtaining the interference estimation I1associated with S1 transmission. The ratio of S1 and I1 plus noise (withproper combining applied, if any, and in the power domain) is then theSINR associated with S1 transmission. Other SINRs may be obtainedsimilarly. Also, other measurement quantities including, but not limitedto, CQI, CSI, PMI, RI, BI, and RRM measurements may be obtained.

To conclude, NZP CSI-RS REs may be used for interference measurements.The UE behavior may need to be clarified in such a case. These conceptsmay apply to two cases: TM10 or its evolution, with a CSI-IM thatoverlaps with the CSI-RS, and TM9 or its evolution, with no CSI-IMconfigured.

An embodiment method for downlink signaling in a wireless networkincludes signaling to a UE an index of a CSI-IM resource, CSI-RSresource, or CQI report/CSI process, together with a timing and/or atime period, wherein the UE measures and feeds back based on theresources associated with the indexes and timing, the UE assumes a newmeasurement condition for the indicated CSI-IM resource, CSI-RSresource, or CQI report/CSI process will be in effect since theindicated timing and/or according to the indicated time period, and theeNB adapts its transmissions (e.g., precoding, muting or non-muting)based on the indicated CSI-IM resource and/or CSI-RS resource accordingto the indicated timing and/or timing period.

An embodiment of a method for backhaul signaling in a wireless networkis disclosed that includes signaling to a second eNB of a CSI-IMresource and/or CSI-RS resource, together with the timing and/or a timeperiod, wherein the second eNB sends a DL signaling to a UE. In anotherembodiment of a method for backhaul signaling in a wireless network isdisclosed that includes signaling to a second eNB of a CSI-IM resourceand/or CSI-RS resource, together with the same timing and/or a timeperiod, wherein the second eNB sends a DL signaling to a UE.

An embodiment method for backhaul signaling in a wireless networkincludes signaling to an eNB of an CSI-IM resource and/or CSI-RSresource, together with a timing, wherein a plurality of eNBs adapttheir PDSCH transmissions (e.g., precoding, muting or non-muting)according to the transmissions on the indicated CSI-IM resource and/orCSI-RS resource at the indicated timing, and the eNBs signal UEs to stopthe measurements and feedback according to the timing. In any case, ifthe timings are signaled, the timings may be signaled once at thebeginning of the probing process (e.g., a sequence of timings of t0, t1,. . . , tk with a predetermined k), or signaled over time when needed.

In an embodiment method, the timing exchanged by eNBs and/or the timingexchanged between the eNBs and UEs are not present. This embodiment hasthe benefit of less signaling overhead. However, the probing may becomelengthier in time and more likely to fluctuate. On the other hand, thetiming may be either predefined or partially predefined so that eitherno signaling about timing or a simplified signaling about timing may beused. Thus the signaling overhead may be reduced.

Various embodiments of this disclosure provide systems and methods forchannel measurement in a wireless network. In particular, a method andsystem for interference measurement of a channel in the wireless networkare provided.

Performance in a wireless network may refer to measures of QoS and maybe indicated by different ways of measuring the QoS. For example, theQoS, and thereby performance, of the wireless network may be indicatedby measuring the bandwidth, throughput, latency, jitter, error rate, andother suitable metrics of the network. As a particular example, an errorrate may be counted based on a number of received bits of a datatransmission over a communication channel that may have been altered dueto noise, interference, distortion or synchronization duringtransmission. Among the factors that may cause alteration of a datatransmission, interference may be a fundamental issue. Interference mayrefer to anything which may disrupt or otherwise modify a signal as ittravels along a channel between a transmitter and a receiver in aprocess of communication. For example, interference may include, but isnot limited t0, noise, distortion, or other factors. In certainembodiments, interference refers to an addition of unwanted signals to auseful signal. Interference measurement (IM) may be important forresource management, including for reducing and controlling channelinterference.

A method for adaptation in a wireless network may include a first basestation signaling information of a first resource set to a first UEand/or a second base station, and the second base station signalinginformation of a second resource set to a second UE and receivingfeedback from the first and second UEs for the resource sets. The methodincludes the first base station signaling a first timing to the first UEand/or the second base station, and the second base station signalingthe first timing to the second UE and receiving feedback from the firstand second UEs about the resource sets according to the first timing.The method further includes the first base station transmitting a firstsignal on a first subset of the first resource set according to thefirst timing, and the second base station transmitting a second signalon a second subset of the second resource set according to the firsttiming and receiving feedback from the first UE about the transmittedfirst signal, the first resource set, and the first timing. The methodfurther includes the first base station transmitting a third signal on athird subset of the first resource set according to the first timing,the second base station transmitting a fourth signal on a fourth subsetof the second resource set according to the first timing, the first basestation signaling a second timing to the first UE or the second basestation, and the second base station signaling the second timing to thesecond UE and receiving feedback from the UEs according to the secondtiming after the UEs stop measurements.

The resource set may be a resource block that includes a set of REs. Incertain embodiments, an RE may be defined by a time and frequencyresource within a subcarrier and an OFDM symbol. For example, twelvesubcarriers in a slot may form a resource block.

A method for downlink signaling in a wireless network may include a UEreceiving from a base station signaling of an index of a CSI-RSresource, CSI-IM resource, a CQI report, or a CSI process, together witha timing. The method further includes measuring and sending feedback tothe base station in accordance with the indexed resource and the timing,assuming a new measurement condition for the indexed resource will be ineffect according to the timing, and receiving adapted transmissions fromthe base station on the indexed CSI-IM resource and/or CSI-RS resourceaccording to the timing.

Capacity power may function at zero-power (ZP) or non-zero-power (NZP)for a channel in a network. A node may cost power to remain ON to listento transmissions from other nodes in a network.

Often interference measurement is taken when capacity power of a channelfunctions at ZP. A channel may transmit data when capacity power of thechannel functions at NZP. In certain embodiments, it may be beneficialfor interference measurement to be performed in association with datatransmission (e.g., when capacity power of a channel functions at NZP).By doing so, more information may be gathered for resource managementfor reducing and controlling channel interference.

For example, interference measurement may be performed on more than twoREs, and IM values of the more than two REs may be obtained. An averagevalue of the obtained IM values may be calculated, which may provide areference for the interference estimation. Additionally oralternatively, all IM values may be gathered and added together to havea complete reference number of the transmission quality. Additionally oralternatively, a portion of the IM values may be gathered and added togenerate a reference number of the transmission quality. Additionally oralternatively, both average value and a relative addition of a pluralityof IM values may be generated for similar purpose. Such solutions may beperformed from the perspective of a UE or a network.

Several embodiments of CM and IM are described below.

A general guideline for configuration for channel measurement (CM) andIM may be as follows. A set of non-zero-power (NZP) CSI-RS resource(s)is configured to a UE for channel and interference measurements, and aset of ZP CSI-RS resource(s) is configured to the UE for IM. A subset ofthe set of NZP CSI-RS resource(s) are configured for channelmeasurement. Another subset of the set of NZP CSI-RS resource(s) and asubset of the set of ZP CSI-RS resource(s) are configured forinterference measurement. The wireless network indicates, via DCI or acombination of MAC and DCI, the subset of NZP CSI-RS resource(s) forchannel measurement, and the subset of NZP CSI-RS resource(s) and thesubset of ZP CSI-RS resource(s) for interference measurement. In someembodiments, the DCI indication may be a dynamic triggering of one ormore CSI reporting settings. In some embodiments, some CSI-RS resourcesfrom two NZP CSI-RS resource subsets may overlap.

In certain embodiments, UE may assume each port of a channel measurementNZP CSI-RS resource corresponds to a desired interference transmissionlayer if no PMI and RI feedback is configured or indicated. In someembodiments, a UE may assume each port of interference measurement on anNZP CSI-RS resource corresponds to a certain interference transmissionlayer if the NZP CSI-RS resource for IM is not overlapped with the NZPCSI-RS resource for CM. There may be multiple ways to specify UEbehavior and/or UE assumptions. As a first example, the operations thatthe UE performs may be directly specified. As a particular example ofdirectly specifying the operations to be performed by the UE, thedirectly-specified operations may be the following: the UE extractsinterfering signals on each NZP CSI-RS resource for IM as a first step,and the UE sums the interfering signals applying weights as a secondstep, and so on. In this way, in certain embodiments, the UE may notneed to make UE assumptions, or UE assumptions do not need to bestandardized, but a UE's behavior may be standardized. On the otherhand, a UE's assumptions may be provided based on which UE may havesufficient information to operate. A UE's assumptions may infer the UE'sbehavior, and vice versa.

The above-referenced interference transmission layer also may bereferred to as an interference layer, layered interference, atransmission layer from an interferer, a precoded/beamformedinterference, a stream from an interferer, an interference stream, aninterference transmission stream, and so on. In certain embodiments, theinterference transmission layer is similar to a transmission layer(e.g., stream) from a serving network point, but in the case of aninterference transmission layer, the transmission (e.g., stream) isintended for another recipient and hence this layer becomes interferenceto an interfered UE. In other words, when a network point transmits astream (e.g., via MIMO precoding or beamforming) to a served UE, thisstream becomes an interference transmission layer to another UE notintended to receive the message of the stream. If ZP IMR or legacy CRSbased IM is used for IM, the interference transmission layer might bemixed with other interference and might not be seen by the UE (e.g., UEhas no information about this layer but can see aggregatedinterference). With NZP IMR, the UE may have sufficient information andcapability to see the interference transmission layer. In certainembodiments, each interference transmission layer is associated with aninterference transmission signal and an interfering channel. Asexamples, each layer in H_(k)W_(i)S_(i) ofY_(k)=H_(k)W_(k)S_(k)Σ_(i≠k)H_(k)W_(i)S_(i)+I_(k)+n_(k) (see below) isan interference transmission layer, and each layer in H1 S1 and H2 S2 inY=HSS+H1 S1+H2 S2+I0 (see below) is an interference transmission layer.Each port in the NZP IMR may correspond to an interference transmissionlayer

On an NZP CSI-RS resource that is for channel measurement, the UE mayassume its desired signal(s) is transmitted. In other words, the NZPCSI-RS resource to be used by the UE for CM is transmitted according tonetwork configuration/indication, including, for example, scrambling ID,layers/ports, CDM, Pc (‘powerControlOffset’, or EIRP ratio between anNZP layer energy on an RE and PDSCH energy on an RE), etc. In certainembodiments, no further assumption may need to be made by the UE.Consequently, the UE may extract each of the NZP signal layers on theassociated port using the scrambling ID and CDM port mappinginformation, and assumes the signal is boosted by Pc as being signaled.In certain embodiments, the power boosting is removed when forming achannel matrix Hs so that Hs corresponds to actual PDSCH transmissionpower. For NZP CSI-RS, the following RE patterns may be considered. TheRE pattern for an X-port CSI-RS resource includes one or multiplecomponent CSI-RS RE patterns. The component CSI-RS RE pattern (Y, Z) maybe defined within a single PRB as Y adjacent REs in the frequency and Zadjacent REs in the time. In NR, CDM of 1, 2, 4, 8 are supported for NZPports of 1, 2, 4, 8, 12, 16, 24, 32. Frequency-domain CDM, time-domainCDM, and F/T-domain CDM may be supported.

Density [RE/RB/port] N (Y, Z) CDM >1, 1, ½ 1 N.A. No CDM 1, ½ 1 (2, 1)FD-CDM2 1 1 (4, 1) FD-CDM2 1 1 (2, 1) FD-CDM2 1 2 (2, 2) FD-CDM2, CDM4(FD2, TD2) 2 1 1 (2, 1) FD-CDM2 2 1 2 (2, 2) CDM4 (FD2, TD2) 6 1, ½ 2(2, 2) FD-CDM2, CDM4 (FD2, TD2) 4 1, ½ 4 (2, 2) FD-CDM2, CDM4 (FD2,TD2), CDM8 (FD2, TD4) 2 1, ½ 4 (2, 2) FD-CDM2, CDM4 (FD2, TD2), CDM8(FD2, TD4)

The following provides two examples of how NZP may be used for IM:

In an embodiment, a first type of how NZP may be used for IM isillustrated when an NZP CSI-RS signal is based on IM. In this case,information about the interfering NZP CSI-RS signal, such as thescrambling ID, ports/layers, power boosting value, etc., is signaled toan interfered UE, and the interfered UE performs IM based on thesignaled information and received NZP CSI-RS signal.

In an embodiment, a second type of how NZP may be used for IM isillustrated when an NZP CSI-RS resource is based on IM. In this case,the interfering NZP CSI-RS signal information may or may not be signaledto the interfered UE, but at least the NZP resource information issignaled to the interfered UE, so that the interfered UE knows on whichresources (e.g., REs) to perform IM. The UE may utilize part of the NZPCSI-RS signal information (if signaled) in IM.

In certain embodiments, the first type of NZP-based IM (e.g., when a NZPCSI-RS signal is based on IM) may have an advantage of more accurateestimation of dominant interference, such as by estimating theinterfering channel matrix H from the closest interferer (e.g., theclosest interfering UE) and, possibly, performing advanced receiverrelated operations. In some scenarios, however, there remain issues forimprovement for the first type of process. First, when the UE extractsthe NZP CSI-RS signal for IM, the UE behavior may involve advancedreceiver related operations. For example, CSI may be derived with theextracted interfering channel matrix, non-dominantinterference-plus-noise may be estimated (such as obtained on a ZP forIM, or on this NZP CSI-RS resource with NZP CSI-RS signal discounted).Second, when the UE does not extract the NZP CSI-RS signal for IM, theUE may obtain interference energy/power on the NZP CSI-RS resource. Inthis scenario, the process of the second type may, in some situations,perform better than the process of the first type. In this case the UE'sassumption and behavior may be different from those scenarios when thesignal may be extracted.

There may be multiple reasons for the UE to be unable to extract theinterfering NZP CSI-RS signal. Such reasons may include limited UEcapability, insufficient strength of interference (but not negligible,either), or other suitable reasons. Interference power may be low, suchas due to interference coordination and avoidance, orthogonal pilots/RS,or other reasons. In multi-user (MU) operation, users often arespatially separated (e.g., the users are associated with differentspatial precoding), and the beamforming for UE1 may be largelyseparated, or even nearly orthogonal from the beamforming for UE2. Dueto beamforming in a network, the interference that a UE experiences mayseem weaker than those CSI-RS targeted at the UE itself. In somescenarios, a poor channel estimation of performance may make suchoperation infeasible.

The second type of how NZP may be used for IM (e.g., when a NZP CSI-RSresource is based on IM) may have an advantage in which information suchas interfering signal scrambling ID, ports/layers, power boosting value,and other suitable information may not need to be transmitted to orutilized by the UE. Two example cases are described below.

Example case 1: IM is obtained after extracting a serving signal. Inthis case, the serving signal overlaps, at least in part, with theinterference measurement resource (IMR). After the serving signal isextracted, the remaining energy/power on the NZP resource REs isutilized to obtain IM.

Example case 2: IM is obtained on the IMR without extracting a servingsignal. In this case, the IMR REs contain only interference, and the UEmay estimate the energy/power on the IMR REs to obtain IM. The UEassumption and behavior on this resource may be more advanced thanZP-based IM, which will be described later.

Embodiments for IM based on ZP CSI-RS are provided. There are a fewexample cases. In a first example, IM is based on one ZP CSI-RS. At thenetwork side, the ZP-based IM for a cell may be overlapped with one ormore neighboring cells' data transmission. The ZP-based IM in thisexample may reflect a current interference condition but potentiallydoes not reflect a future or a prospective interference condition. TheUE may perform IM on the ZP CSI-RS by measuring the energy/power on theZP CSI-RS REs.

FIG. 20 shows an example case 2000 for IM based on ZP CSI-RS, accordingto certain embodiments of this disclosure. Four REs 2002 (RE 2002 a, RE2002 b, RE 2002C, and RE 2002 d) of the ZP CSI-RS are shown which mayobtain four IM values (IM1-IM4). In certain embodiments, the UE assumesthat the interference conditions on the four REs 2002 are the same, anddetermines an interference value (I) by performing an averagingoperation based at least on the four IM values. For example, the UEgenerates I=(IM1+IM2+IM3+IM4)/4. There may be multiple sets of 4 REs2002 for the ZP CSI-RS, and the REs 2002 across the multiple sets mayhave the same IM measurement restriction condition. In certainembodiments, the UE assumes that the interference conditions on all theREs 2002 are the same, and determines an interference value (I) byperforming an averaging operation over all such REs 2002.

Additionally or alternatively, at the network side, the ZP-based IM fora cell may be overlapped with RS transmission(s) of one or moreneighboring cells. The RS transmission of a neighboring cell may includeNZP CSI-RS, DMRS, or other suitable RS transmissions. The ZP-based IMreflects current or future interference conditions depending on whetherthe RS is used for current data transmission or future datatransmission. In FIG. 20 , NZP is transmitted by the neighbor cell, andeach RE 2002 is associated with one layer (e.g., no CDM for NZP, andeach RE 2002 is for a layer or a port). This solution may be extended toDMRS or CDMed NZP. In certain embodiments, the 4 layers may havedifferent interference to the UE, since each layer may be beamformeddifferently from each other. This may apply to interference from a samecell or a different cell serving multiple UEs on the same time andfrequency resources, or on the same frequency resources but separatelyin time domain (e.g., MU-MIMO).

FIG. 21 illustrates an example of a UE measuring the energy/power on ZPCSI-RS REs, see elements 21A, 21B, and 21C, according to certainembodiments of this disclosure. On the four REs 2102 (RE 2102 a, 2102 b,2102C, and 2102 d) of the ZP CSI-RS 2100 (see element 21A), the UE mayobtain four IM values, IM1-IM4. In some scenarios, it may not beappropriate for the UE to sum the energy/power to obtain the actualinterference (e.g., I=IM1+IM2+IM3+IM4), as the I0 energy/power would becounted for four times in the obtained I. Without further informationabout the interference condition, the UE may assume that theinterference associated with data transmission corresponds to theaverage value of the energy/power obtained on the 4 REs 2102 (e.g.,I=(IM1+IM2+IM3+IM4)/4).

However, to potentially improve the meaningfulness of the averagingoperation, the network may attempt to ensure that the averagecorresponds to the data transmission with all four layers on the sameRE. Therefore, each layer 2106 of the NZP CSI-RS 2104 may bepower-boosted by four times or 6 dB (as an example) to match the powerlevel of a PDSCH transmission. In some scenarios, other power boostvalues may not provide for accurate IM. In certain embodiments, the UEmay not need to know the power boost value and may not need to know thepresence of NZP/DMRS/PDSCH on overlapping REs 2102, but assumes that theinterference conditions on the four REs 2102 may or may not be the same,and the average on the four REs 2102 corresponds to the interferencecondition of PDSCH associated with the IMR REs 2102. There may bemultiple sets of four REs 2102 for the ZP CSI-RS and the REs 2102 mayhave the same IM measurement restriction condition. The UE may assumethat the interference condition obtained by averaging on all the REs2102 is the desired interference condition, and performs averagingoperation over all such REs 2102.

For a DMRS-based PDSCH transmission mode (e.g., transmission modes 9 and10 as specified in 3GPP LTE standards, if UE-specific RSs are present inthe PRBs upon which the corresponding PDSCH is mapped, the UE may assumethe ratio of PDSCH energy per resource element (EPRE) to UE-specific RSEPRE within each OFDM symbol containing UE-specific RS is 0 dB for anumber of transmission layers less than or equal to two and −3 dBotherwise. A similar principle may be adopted here. In certainembodiments, the UE assumes interference is transmitted on the ZP REs2102 without further knowledge on additional power boosting/covariancematrix/spatial correlation/etc. for the interference. The UE may assumea weighted sum (or average) of energy/power on the ZP REs 2102corresponds to the desired interference hypothesis. The UE may performweighted sum (or average) of energy/power on the ZP REs 2102 to obtainthe desired interference hypothesis. This UE operation may be aconsequence of UE assumption that interference is transmitted on the ZPREs 2102 without further knowledge of the interference. In certainembodiments, without further knowledge on additional power boosting, theUE may assume the interference has 0 dB power boosting for each RE 2102.

Embodiments of IM based on multiple ZP CSI-RSs are provided. In someembodiments, the UE behavior and the corresponding setting are similarto those with one ZP CSI-RS (e.g., the UE may assume that theinterference condition obtained by averaging on all the REs is thedesired interference condition) and performs an averaging operation overall such REs. Some of the ZP CSI-RSs may be overlapping with neighboringcells' PDSCH regions, which actually corresponds to the interferenceconditions that may be averaged. If some of the ZP CSI-RSs may beoverlapping with neighboring cells' RS regions, different ZP CSI-RSs areactually associated with different interference conditions.

In some embodiments, however the UE may not need to know the difference,and simple averaging may still be meaningful (e.g., when the RSs arepower boosted properly to account for the reuse factor over all such ZPCSI-RSs). For example, if a layer of the RS is only on n REs out of theM REs for ZP CSI-RSs, then it may be appropriate to boost the layer M/ntimes, which may be the UE assumption for performing the averagingacross all ZP CSI-RSs but may not be desirable considering other UEs' ZPCSI-RS patterns. In this case, certain operations may be indicated bythe network. For example, the UE may first perform averaging within eachZP CSI-RS, and then perform addition and/or subtraction to obtain anactual value of interference, such as ZP1+ZP2−ZP3, in which the additionto sum up the interference power/energy on two ZP CSI-RSs, and thesubtraction may resolve the double-counting of noise and interferencecommon to all ZP1˜ZP3. For ZP1 and ZP2, there may be overlapping withinterfering RS1 and interfering RS2 on orthogonal time/frequencyresources, and each RS may be power boosted according to its own reusefactor, and ZP3 may not contain RS1 or RS2. The network may indicate theoperations, averaging, addition, and/or subtraction, for each ZP CSI-RS,such as (+,+,−) in above example. If there is an additional ZP4 with thesame hypothesis as ZP3, ZP3/ZP4 may be indicated to be averaged firstbefore being subtracted (e.g., (ZP1+ZP2−(ZP3+ZP4)/2) or (+1, +1, −½,−½)). If ZP1-ZP3 are for RS1˜RS3 orthogonalized in time/frequencydomain, ZP4 is for other interference, then (ZP1+ZP2+ZP3−2ZP4), or(+1,+1,+1, −2), may be indicated. In a generalized way, when a ZP isadded M times, then the ZP CSI-RS is to be subtracted M−1 times, so thatno redundant addition is performed for the interference measurement. Inthis case, M is 3 for the addition part in the example“ZP1+ZP2+ZP3-2ZP4”, while M−1 is 2 for the subtraction part of“ZP1+ZP2+ZP3-2ZP4”.

If ZP1-ZP3 are for RS1-RS3 orthogonalized in time/frequency domain,ZP4/ZP5 are for other interference, then (ZP1+ZP2+ZP3−ZP4−ZP5), or(+1,+1,+1, −1,−1), may be indicated. Note that more overhead may be usedto signal −2 or −½ or other fractions, which may be more suitable forRRC/MAC configuration signaling than for PHY DCI signaling. Additionallyor alternatively, the network might signal the types of ZP CSI-RSs: typeone for RS orthogonalized in time/frequency domain, type two forresources blanking for type one RS, and UE may sum up all type one ZPCSI-RSs, subtract one less times the mean of all type two ZP CSI-RSs. Incertain embodiments, with the defined UE behavior, the network needs tosignal + or − (1 or −1, or equivalent).

The UE assumes interference is transmitted on the REs of multiple ZPCSI-RSs for IM without further knowledge on additional powerboosting/covariance matrix/spatial correlation/etc. for theinterference. The UE may assume weighted sum (or average) ofenergy/power on the REs for all ZP CSI-RSs corresponds to the desiredinterference hypothesis. The UE may perform weighted sum (or simpleaverage) of energy/power on the ZP CSI-RS REs to obtain the desiredinterference hypothesis. This UE operation may be a consequence of UEassumption that interference is transmitted on the ZP CSI-RS REs withoutfurther knowledge of the interference. Note that without furtherknowledge on additional power boosting, the UE may assume theinterference has 0 dB power boosting for each RE of each ZP CSI-RS forIM. Additionally or alternatively, if the network provides the UE withinformation such as ZP1 is for a first part of interference and ZP2 isfor a second part of interference, then UE may sum up the mean energy onthe ZP CSI-RSs to obtain the interference associated with desiredinterference hypothesis. If the network provides the UE with informationsuch as ZP1 is for a first part of interference, ZP2 is for a secondpart of interference, and ZP3 is for common interference for ZP1 andZP2, then UE may sum up the average energy on ZP1/ZP2 and then subtractthe average energy on ZP3 to obtain the interference associated withdesired interference hypothesis.

Embodiments for IM based on NZP CSI-RS and in which the NZP CSI-RS isnot overlapped with NZP CSI-RS for CM are provided. To signal a NZPCSI-RS for IM to a UE, in addition to NZP CSI-RS resource configurations(ports, time/frequency resources, etc.), the scrambling ID may besignaled so that the UE may extract the RS signal (e.g., this RS signalshould not be confused with the intended signal for CM; here the RSsignal serves as an interference signal). With the interference signalextracted, the UE may estimate the interference channel matrix (e.g.,this interference channel matrix should not be confused with theintended channel for CM; here the interference channel matrix serves asan interference channel measurement).

Based on this estimated interference channel matrix, the UE may performinterference rejection. For example, a potentially more accurateinterference covariance matrix may be obtained for interferencecancellation. The NZP power boosting relative to PDSCH power level maybe signaled. For example, on a 4-port NZP CSI-RS, layers 1/2 are CDMedon two REs, and layers 3/4 are CDMed on the other two REs. Each layermay be boosted by 3 dB, and the resulting per-RE power is the same asthe associated PDSCH with all four layers on each RE. The power boostingmay not be signaled if the default-defined UE assumption is to assume apower boosting to PDSCH level. Then with a total of N layers on N REs,with each RE carrying only n (<=N) layers, a power boosting of N/n timesmay be assumed. This is related to the CDM design (e.g., in this casethe CDM is across every n layers). In LTE NZP CSI-RS, n=2, and for DMRSit is 1/2/4. In NR, CDM of 1, 2, 4, 8 are supported for NZP CSI-RS portsof 1, 2, 4, 8, 12, 16, 24, and 32. Frequency-domain only CDM,time-domain only CDM, and F/T-domain CDM are supported. In general, theCDM value and its type may be signaled to UE for a NZP CSI-RS. The CDMinformation and NZP CSI-RS port information may then be used by the UEto figure out the implicit power boost. For example, for 32 port NZPCSI-RS and CDM 8, each layer is boosted by 4. However, if the networkneeds more flexibility in power boosting, then the power boosting valueneeds to be explicitly signaled to UE. Furthermore, even if a NZP CSI-RSfor IM is signaled to a UE, the UE may not be able to extract the NZPCSI-RS interference signal sufficiently reliably as the interference maynot be strong enough (but still not negligible). Some UEs withoutadvanced receiver capability or having NZP CSI-RS measurement capabilitylimitations may not be able to extract the NZP CSI-RS either. Therefore,an NZP CSI-RS for IM may or may not be extractable by a UE, and foreither case, embodiments are provided.

First, cases in which IM is based on one NZP CSI-RS and the NZP CSI-RSis not overlapped with NZP CSI-RS for CM are provided. If the UE cannotextract the NZP CSI-RS for IM, then the UE behavior and assumption forthe NZP CSI-RS may be the same as those for a ZP CSI-RS. The UE mayassume that interference signal(s) is transmitted on the NZP CSI-RS forIM, and each port of the NZP CSI-RS is for one interference layer. TheUE may assume that each interference layer is power boosted according tothe factor of #ports/CDM. In another embodiment, the UE may assume thateach interference layer is power boosted by 0 dB and each RE containsall layers of interference. In either case, the UE may assume that theinterference condition obtained by averaging on all the REs is apreferred result.

The UE may perform an averaging operation over all such REs.Correspondingly, the network may ensure the correct power boosting(e.g., boost to PDSCH level and according to #ports/CDM). This value mayor may not be signaled to the UE, as the UE may derive from NZP CSI-RSconfiguration/indication. The UE may overwrite/ignore if a differentvalue is received. Additionally or alternatively, the UE may performaveraging if the power boosting value is the same as #ports/CDM. Ifother values are used by the network, even though the values aresignaled to the UE, the UE still may not obtain an unbiased estimate ofinterference, as on the NZP CSI-RS REs, interference boosted not toPDSCH level (the NZP CSI-RS signal) and other interference boosted toPDSCH level and noise are superposed and not separable. On the otherhand, if the UE may extract the NZP CSI-RS for IM, then the UE mayseparate the NZP CSI-RS and leftover interference and noise I0. Forexample, the UE may estimate the interference channel HI, and formulateY=HSS+HI SI+I0,

where Y is the received signal, HSS is the intended channel matrix(obtained from CM resources) times intended signal, HI SI is theinterference channel matrix (obtained from IMR of NZP CSI-RS) timesinterference signal, and I0 is the noise plus other interference (e.g.,all interference plus noise except for the interference associated withNZP signal HI SI). HI may be obtained by averaging over multiple NZPCSI-RS REs satisfying the signaled measurement restriction, layer bylayer (e.g., UE assumes each port of NZP CSI-RS is associated with aninterference condition) but not cross layers. For I0 it may be averagedover all IMR REs assuming the same interference condition as on ZPCSI-RS. Based on the above equation the UE may perform interferencerejection in the CSI measurement and CQI/RI/PMI computations. Theperformance is expected to be better than ZP-based IM and NZP-based IMin which the signal is not extractable. As the UE may extract the NZPCSI-RS, any power boost value may be used and signaled to the UE. Withpotentially higher power boosting, the estimation of HI may be moreaccurate, but the extra boosting may be discounted in HI so that the UEwould not assume higher interference. In some scenarios, however, thismethod is not robust enough to cover certain other cases, so in certainembodiments it may be desirable to boost NZP CSI-RS to PDSCH level.

FIG. 22 illustrates an example 2200 of IM based on multiple NZP CSI-RSsand not overlapped with CMR, according to certain embodiments of thisdisclosure. Two NZP CSI-RSs for IM are illustrated in this example (afirst corresponds to row 2202 a and a second corresponds to row 2202 b).FIG. 22 shows four columns 2204 (column 2204 a, column 2204 b, column2204 c, and column 2204 d) from perspectives of a serving cell 2206,interferer 1 2208, interferer 2 2210, and a plurality of remoteinterferers 2212, respectively.

On the NZP CSI-RSs, the serving cell mutes, while the interferers (whichmay be the same cell as the serving cell or a different cell than theserving cell) transmit on one of the NZP CSI-RSs and mutes on the other.In this case, the UE assumes no serving signal is transmitted on the NZPCSI-RS for IM, and an interference signal(s) is transmitted on the NZPCSI-RS for IM. If NZP CSI-RS interfering signal information is signaledto the UE, such as scrambling ID, layers/ports, CDM, Pc, suchinformation can also be assumed by the UE (e.g., similar assumptions asCM NZP CSI-RS signal but the assumptions are for IM instead). In certainembodiments, no other assumption is made by the UE regarding theinterference signal. In certain embodiments, if any of above informationis not signaled to the UE, the UE does not make the associatedassumption for IM.

Certain embodiments depend on whether the UE may be able to extract bothNZP CSI-RSs, neither NZP CSI-RS, or one of the NZP CSI-RSs. If both maybe extracted, a UE may estimate both interfering channel matrices H1 andH2, and obtain leftover interference and noise I0 by averaging theenergy/power on the NZP CSI-RSs discounting the NZP CSI-RS signals. I0is the noise plus other interference (e.g., all interference plus noiseexcept for the interference associated with neither NZP CSI-RS signal).A UE may formulate the following:Y=HSS+H1S1+H2S2+I0.

In this example, interference rejection/cancellation may be performedfor CSI measurement and computation. If neither NZP CSI-RS is extracted,then in some scenarios the UE may obtain (I1+I0) on NZP1, where I1 andI0 are not separable, and UE may obtain (I2+I0) on NZP2, where I2 and I0are not separable. Summing up (I1+I0) and (I2+I0) may lead to doublecounting of I0, potentially making averaging an appropriate technique.This implies that (I1+I2)/2+I0 may correspond to the actual PDSCHinterference condition. A matrix rank-based argument may illustrate thatthis is not possible with four times of power boosting (corresponding toboosting to PDSCH level of that interferer), and instead this uses eighttimes of power boosting for the NZP CSI-RSs, where the eight comes fromthe reuse factor for NZP CSI-RS interference signals accounting both NZPCSI-RSs, not one NZP CSI-RS from one interferer. In some scenarios,however this boosting may cause bias to another UE that is configuredwith one of the NZP CSI-RSs for IM, and hence may not desirable in somescenarios. If one of the NZP CSI-RSs is extracted (e.g., NZP1 isextracted but NZP2 is not extracted), then the UE may separate I1 and I0NZP1, but (I2+I0) on NZP2. The UE may formulate the following:Y=HSS+H1S1+(I2+I0).

In this example, interference rejection/cancellation may be performed.Therefore, it may be desirable to adopt different UE behaviors based onthe extractability of the NZP CSI-RSs as described above, and there maybe cases in which unbiased interference estimation is difficult or notpossible to obtain. Therefore, such configurations of IM may havelimited benefits in practical situations.

Embodiments for IM based on one or more NZP CSI-RSs and one or more ZPCSI-RSs, and in which none is overlapped with the NZP CSI-RS for CM, areprovided. In certain embodiments, this approach may overcome somechallenges described above, and may improve the IM accuracy, at thepossible price of higher measurement overhead. In some embodiments, theZP CSI-RS(s) is specified to have the interference condition includingall interference on the NZP CSI-RS IMRs. If any of the NZP CSI-RS is notextractable, the ZP CSI-RS(s) may be used to measure and average theinterference. If all the NZP CSI-RSs are extracted, then the NZP CSI-RSinterfering signals may be individually averaged and then summed upacross all the NZP CSI-RSs, and the leftover interference plus noise onany or all of the NZP CSI-RSs may be averaged to obtain I0. The ZPCSI-RS(s) may also be used to obtain average leftover interference plusnoise, by subtracting energy/power of the signals associated with NZPCSI-RSs (after removing the power boosting). In some other embodiments,the ZP CSI-RS(s) is specified to have the interference conditionexcluding all interference on the NZP CSI-RS IMRs.

If any of the NZP CSI-RS is not extractable, the UE may assume all NZPCSI-RSs are ZP CSI-RSs overlapping with RS, and similar to the multipleZP CSI-RSs for IM, all the NZP CSI-RS(s) and the ZP CSI-RS(s) may beused to perform the specified operations (averaging, addition,subtraction) to obtain the interference in an unbiased way. In otherwords, all the NZP CSI-RSs are regarded as +, and all the ZP CSI-RSs areregarded as −. On the other hand, if all the NZP CSI-RSs are extracted,then the NZP CSI-RS interfering signals will be individually averagedand then summed up across all the NZP CSI-RSs, and the leftoverinterference plus noise on any or all of the NZP CSI-RSs and ZP CSI-RSsmay be averaged to obtain I0. On the network side, the network maycoordinate the NZP CSI-RSs/ZP CSI-RSs/IMRs/CMRs to attempt to ensurethat the signaling (configuration/indication) corresponds to the desiredIM/CM/CSI hypotheses/conditions. To properly orthogonalize, the NZPCSI-RSs and sometimes ZP CSI-RSs may use network coordination andrelatively high measurement overhead.

The above embodiments are for non-overlapped CMRs and IMRs. If CMRs andIMRs may overlap, however, different embodiments, such as thosedescribed below, may be appropriate.

Some embodiments apply to scenarios in which NZP CSI-RS CMR and IMRcompletely overlap and one NZP CSI-RS resource is configured. A UE mayassume that a serving signal(s) for the UE is transmitted on theresource according to the configuration/indication, and an interferencesignal(s) is also transmitted on the resource according to theconfiguration/indication. In other words, the UE performs CM and IM onthe same set of REs of one NZP CSI-RS resource. Throughout thisdescription, the term NZP or NZP CSI-RS may refer to NZP CSI-RS signal,NZP CSI-RS resource, or both NZP CSI-RS signal and NZP CSI-RS resource.In general, the particular meaning will be clear to one of ordinaryskill in the art from the context in which the term is used. In somecases, this disclosure specifies a distinction. For example, in theoverlapped cases, the NZP signal for CM and NZP signal for IM are on thesame NZP resource.

FIG. 23 illustrates an example use case 2300 of overlapped CSI-RSresource for channel and interference, according to certain embodimentsof this disclosure. One NZP CSI-RS resource, as an example, may beconfigured for channel measurement as well as for interferencemeasurement.

Based on prior CSI information, a gNB determines MU transmission on slotn+1 for a set of UEs. On the CSI-RS resource of slot n, the gNBtransmits beamformed CSI-RS for each UE in the MU group. Each UE in theMU group could estimate a channel to obtain the intended signal, as wellas interference by discounting (e.g., by subtracting) the UE's ownintended signal from the received signal. For instance, from UE k'sperspective, the received signal on the NZP CSI-RS may be expressed as:Y _(k) =H _(k) W _(k) S _(k)+Σ_(i≠k) H _(k) W _(i) S _(i) +I _(k) +n_(k),

where Σ_(i≠k) H_(k)W_(i)S_(i) is the MU interference, I_(k) representsinter-cell interference, and n_(k) represents thermal noise. In somescenarios, when the NZP CSI-RS resource is aligned between surroundingcells, and each cell follows the same mechanism to transmit NZP CSI-RS,the term I_(k) may reflect the inter-cell interference that would beexperienced on the future PDSCH slot n+1. Hence, with thisconfiguration, a gNB is able to predict the interference on the futurePDSCH, including both MU interference and inter-cell interference.Another example of this predication capability is described below withreference to FIG. 30 .

It may be noted that different CSI-RS ports (orthogonalized via, e.g.,FDM, CDM) in a CSI-RS resource may be assigned to different users. Forexample, this mechanism may be used for a non-PMI feedback case (e.g.,port index indication per CSI-RS resource may be configured by RRC toselect the CSI-RS port(s) used for RI/CQI calculation per rank),although this disclosure contemplates use of this mechanism in otherscenarios. With such a configuration, channel measurement on assignedCSI-RS ports might not be impacted by other interfering ports.

FIG. 24 illustrates an example use case 2400 for non-overlapped CSI-RSresource for channel and interference measurement, according to certainembodiments of this disclosure. From the UE0 perspective, NZP CSI-RSresource #0 is for channel measurement while NZP CSI-RS resource #1 and#2 for interference measurement. When a gNB emulates potential MUsignals on NZP CSI-RS resources #1 and #2, UE0 may probe MU-interferenceby measuring interference on these two IM resources.

In some situations, however, inter-cell interference might not be fullycaptured in this way, even if the set of NZP CSI-RS resources is alignedwith the neighboring cells' NZP CSI-RS resources.

FIG. 25 illustrates an example use case 2500 showing inter-cellinterference in a configuration with non-overlapped CMR and IMR,according to certain embodiments of this disclosure. In this scenario,the configuration of CSI-RS resources in cellM 2502 are the same as incello 2504, where resource #0, #1 and #2 are assigned to UEx, UEy andUEz for channel measurement. Users in cello also use these resources toprobe the interference from cellM. However, from UE0's perspective, theinter-cell interference from cellM that are actually serving UEy and UEzis captured. The missing interference from UEx may result in theinaccurate probing of inter-cell interference. If, on the other hand,the set of NZP CSI-RS resources in cello is orthogonal to theneighboring cells' NZP CSI-RS resources, UE0 then may be configured withfive NZP CSI-RS resources for IM to measure intra-cell MU interferenceand inter-cell interference from cellM. In general, if M interferingcells are in UE0's neighborhood, and each cell supports N UEs, (M+1)NNZP CSI-RS resources for IM are configured for UE0, leading topotentially undesirable overhead and complexity.

Probing inter-cell interference (especially fast varying inter-cellinterference) may be an important characteristic of NZP CSI-RS basedinterference measurement. Probing inter-cell interference and/or MUinterference may improve link adaptation. Thus, to realize the gain ofbetter link adaptation, particularly for those cells that are capable ofaligning NZP CSI-RS configuration, embodiments of this disclosuresupport overlapped CSI-RS resource(s) for channel and interferencemeasurement.

A UE's assumptions and behavior for NZP-based IM may be defined in astandard specification. As described above, an NZP CSI-RS signal basedon IM (in fallback mode and non-fallback mode) may be consideredseparately. For an NZP CSI-RS resource based on IM, both overlapped andnon-overlapped may be considered.

Case 1: IM is obtained after extracting a serving signal

In this case, the UE extracts the serving signal on the NZP CSI-RS, andthe leftover energy/power on the REs is to be used to obtain IM. Case 1includes the following two scenarios:

Case 1-1: IMR and CMR completely overlap. In this scenario, the UE mayassume the interference condition after discounting the serving signalcorresponds to the actual interference condition, and further operations(except for averaging on all IMR REs) related to IM may be avoided, ifappropriate.

Case 1-2: IMR and CMR partially overlap. In this scenario, afterdiscounting the serving signal on some IMR REs, the UE obtainsinterference on additional IMR REs, and potentially on all the IMR REs.

The UE could adopt the addition/subtraction approach described above forCase 2 (described below), which uses additional network signaling andassociated UE behavior. This addition/subtraction approach may getcomplicated if multiple NZPs and ZP(s) are used. For example, for threeNZPs and one ZP, the UE may perform |Y₁|²+|Y₂|²+|Y₃|²−2I². This scenariois similar to multiple ZPs described above, and the designs can bereused for the addition/subtraction approach.

Additionally or alternatively, the UE may assume that it is permissibleto average across all IMR REs to obtain the desired interferencecondition for IM, and the network may attempt to ensure consistency.This approach may simplify UE assumption and behavior.

Case 2: IM is Obtained on the IMR without Extracting a Serving Signal

In this case, the NZP IMR REs contains interference, and the UE mayestimate the energy/power on the NZP REs to obtain IM. Similar to Case1-2, the addition/subtraction approach may be considered, but it may bedesirable to use the simpler averaging approach.

Therefore, in all cases the UE behavior may be unified to be averagingon some, and potentially all, IMR REs. This averaging approach also mayunify the UE behavior on NZP CSI-RS and/or ZP CSI-RS for IM. The basestation implementation may attempt to ensure the IM obtained in this waycorresponds to the desired interference condition. An embodiment is tostandardize the UE behavior of averaging power/energy on all NZPCSI-RS/ZP CSI-RS IMR REs, after discounting serving signal if any.

For CSI-RS resource(s) configured for both channel and interference, theoperation of subtraction may be defined. Then the remainingsignals/power after subtracting intended signal are partial or entireinterference.

For an NZP CSI-RS configured for IM but not CM (e.g., for cases withnon-overlapped IMR and CMR) or configured for IM and CM but with servingsignal subtracted, the summation or weighted summation of extractedinterference ports may be performed by the UE. This approach may be dueto a CSI-RS port corresponding to an interferer layer (e.g.,interference transmission layer), such that the operation of summationor weighted summation potentially reflects the total interference. Anappropriate network implementation may be used to provide this approach.One example of the weighted summation is averaging the interferencepower over all ports, which potentially uses no additional signalingsupport.

For CSI-RS resource(s) configured for both channel and interference, theUE assumes its desired signal(s) is transmitted on the resource andaccording to network configuration/indication, and interferencesignal(s) is also transmitted on the resource and according to networkconfiguration/indication. The UE may perform CM on the resource byextracting the desired NZP CSI-RS signal. Then the remainingsignals/power after discounting desired signal are interference to bemeasured by the UE.

When more than one NZP CSI-RS resource is to be configured forinterference measurement, UE assumptions to allow the UE to properlycombine the interference on NZP CSI-RS resources may be defined.

FIG. 26 illustrates another example configuration 2600 of a set of NZPCSI-RS resources, according to certain embodiments of this disclosure.Taking non-overlapped CSI-RS resources as an example, in cello, NZPCSI-RS resource #0, #1, and #2 are assigned to UE0 (shown at 2602), UE1(shown at 2604) and UE2 (shown at 2606), respectively, for channelmeasurement. For each UE, the other two CSI-RS resources, except for theCSI-RS resource for CM, are IMRs.

For UE0, the interference on resources #1 and #2 may be expressed asY₁=I₁+I_(inter) and Y₂=I₂+I_(inter), respectively. I₁ and I₂ are theinterference for UE1 and UE2, and I_(inter) is the interference from aneighbor cell, which may reflect the downlink interference on ameasurement slot. There is a higher layer parameter pc(‘powerControlOffset’) associated with each NZP CSI-RS resource, whichis interpreted as power offset of NZP CSI-RS RE to PDSCH RE. Hence,assuming p_(c,1), p_(c,2) as the power offset associated with resource#1 and #2, Y1 and Y2 may be represented as follows:Y ₁=√{square root over (p _(c,1))}×I _(PDSCH1) +I _(inter),Y ₂=√{square root over (p _(c,2))}×I _(PDSCH2) +I _(inter)

Since an objective is to measure interference from MU PDSCH, theoperation of weighted summation may be defined as

${{\frac{1}{p_{c,1}}{❘Y_{1}❘}^{2}} + {\frac{1}{p_{c,2}}{❘Y_{2}❘}^{2}}} = {{❘I_{{PD{SCH}},1}❘}^{2} + {❘I_{{P{DSCH}},2}❘}^{2} + {( {\frac{1}{p_{c,1}} + \frac{1}{p_{c,2}}} ) \cdot {{❘I_{inter}❘}^{2}.}}}$When

${{\frac{1}{p_{c,1}} + \frac{1}{p_{c,2}}} = 1},$the result would be MU and inter-cell interference. If the Pc's are thesame, then each is 2 (e.g., a UE can average the interference energy onthe NZP CSI-RS s for IM). Alternatively, if IMR also covers resource #0and the UE can obtain I_(inter) on the resource, then the UE can performweighted sum on all three NZP CSI-RS s for IM, and if

${{\frac{1}{p_{c,1}} + \frac{1}{p_{c,2}} + \frac{1}{3}} = 1},$then unbiased IM can be obtained. If the Pc's are the same, then each is3 (e.g., UE may average the interference energy on the NZPs for IM). Incertain embodiments, the Pc is the reuse factor described above forpower boosting.

Considering a variety of factors such as total number of NZP CSI-RS sfor IM, NZP CSI-RS ports, and CDM factors, each layer may be powerboosted to #ports/CDM, where #ports is for all IM NZP CSI-RSs, and CDMis for the layer. For each NZP CSI-RS, the CDM is the same, and hencethe power boosting or Pc is the same for all layers in that NZP CSI-RS.The UE may assume that each interference layer is power boostedaccording to the factor of #ports/CDM. The UE may perform averagingoperation over all such REs. The UE may overwrite/ignore if a differentvalue is received. Additionally or alternatively, the UE may performaveraging if the power boosting value is the same as #ports/CDM. Fromthe above description, when a gNB configured the correctpowerControlOffset on each NZP CSI-RS interference resource, the UE maycorrectly estimate the interference power. Some restriction on theconfigured ‘powerControlOffset’ for each NZP CSI-RS resource may beappropriate.

Another alternative is to introduce an additional ZP CSI-RS resource toresolve the double-counted inter-cell interference issue. For example,the power of inter-cell interference may be estimated on ZP CSI-RS anddenoted as |I_(inter)|², and the total MU and inter-cell interferencemay be obtained as

${\frac{1}{p_{c,1}}( {{❘Y_{1}❘}^{2} - {❘I_{inter}❘}^{2}} )} + {\frac{1}{p_{c,2}}( {{❘Y_{2}❘}^{2} - {❘I_{inter}❘}^{2}} )} + {{❘I_{inter}❘}^{2}.}$In this example, there is no restriction on ‘powerControlOffset’;however, this example uses an additional resource of ZP CSI-RS, and theZP CSI-RS resource may be carefully coordinated among gNBs so that theapproach may accurately capture the intended interference condition forthe UE. In certain embodiments, no additional ZP CSI-RS resource isused, but the CMR is also specified as IMR, and the UE can obtainI_(inter) on the resource.

When a set of NZP CSI-RS resources are aligned between cells, obtainingunbiased inter-cell interference measurement powerControlOffset mightnot necessarily be configured or used on resources with MU interference,or left for gNB implementation. The weighted summation over theinterference on all NZP CSI-RS resources may accurately reflect the MUand inter-cell interference.

When a set of NZP CSI-RS resources in a serving cell is assumed tocollide with a PDSCH of neighboring cells, proper ‘powerControlOffset’may be configured for each NZP CSI-RS resource with MU interference.Then the weighted summation over the interference on all interferenceresources may reflect the MU and a slowly varying part of inter-cellinterference. In certain embodiments, when configuring a NZP CSI-RSresource for IM, scrambling ID, layer/port, or CDM information may notneed to be specified, if Pc powerControlOffset is specified and the Pcis selected to boost the NZP CSI-RS power to PDSCH level. In otherwords, the Pc summarizes the information about CDM and layers/ports. ThePc may be configured for each NZP CSI-RS resource within a NZP CSI-RSresource set. For the same NZP CSI-RS resource within different NZPCSI-RS resource sets, the Pc may be different, since the reuse factormay be different for different resource sets. In other words, Pc may bespecific to an NZP CSI-RS resource set, but might not be specific to anNZP CSI-RS resource. If additional NZP CSI-RS signal information isconfigured/indicated (e.g., scrambling ID, layer/port, or CDMinformation), the additional NZP CSI-RS signal information may bespecified for each NZP CSI-RS resource; in other words, the additionalNZP CSI-RS signal information may be NZP CSI-RS resource specific.

When NZP CSI-RS resource(s) are configured for both channel andinterference measurements, a UE assumes the remaining signals, afterdiscounting serving signal, would be partially or entirely interference

For each NZP CSI-RS resource configured for IM, the UE assumes thesummation or weighted summation of extracted interference ports wouldreflect the interference on this resource.

The UE assumes weighted summation over interference estimated on allresources for interference measurement. A scaling factor associated withNZP CSI-RS Pc may be assumed.

A CSI request field may trigger aperiodic CSI-RS resource set(s) forchannel and/or interference measurement. It may be desirable to indicatewhich resource set among these CSI-RS resource sets is for channelmeasurement and which is for interference measurement. Below are twoexample options for addressing this.

Option-1: each trigger state of a CSI request field would reflect thecombination of {CSI reporting setting, CSI-RS resource set for channel,CSI-RS resource set for interference};

Option-2: each trigger state of CSI request field would indicate CSIreporting setting and this CSI reporting setting associated CSI-RSresource sets. An additional bit-field in the DCI may further select theresource set for channel and resource set for interference.

Both options may support NZP CSI-RS based interference measurement.Option-2 may provide more flexibility on selection of CSI-RS resourcesfor channel or interference measurement. Option-1 may achieve the sameflexibility when sufficient trigger states are supported in the CSIrequest field. RRC signaling, however, may configure each statecorresponding to each measurement hypothesis and reporting setting.Taking component carriers into trigger states, the RRC signalingoverhead and configuration complexity may be a consideration. Therefore,adjacent (or at another suitable location with respect to) the CSIrequest field, an additional bit-field in DCI to further select theresource set for channel measurement and resource set for interferencemeasurement may be introduced.

In some embodiments, all NZP resources for CM/IM are assigned with thesame scrambling ID, which may simplify the UE receiving operation. AnNZP CSI-RS resource set may be assigned with the same scrambling ID. Incertain embodiments, all resources are used for IM, and some layersand/or some resources are used for CM. Different UEs share the samescrambling ID if they are paired in MU mode. Multiple TRPs within aclose neighborhood may share the same scrambling ID on probingresources.

CSI reporting setting(s) may be triggered via DCI. If the CSI reporttrigger is jointly indicated with CSI-RS resource trigger, an IE in DCImay indicate both CSI-RS resource and CSI reporting setting(s).Otherwise, two separate IEs may be used. The number of the CSI reportingsettings may be more than one so as to report multiple CSIs to save CSIreception delay at the gNB side. In one embodiment, a DCI may trigger aCSI-RS resource set. This set may be used for IM, and additional DCIbits indicate a subset of the set for CM. Therefore, in certainembodiments, CMR may be a subset of IMR. In another embodiment, a DCImay trigger a CSI-RS resource set. This set may be used for CM and/orIM, and additional DCI bits indicate a subset of the set for CM andadditional DCI bits indicate a subset of the set for IM. In anotherembodiment, a DCI may trigger a CSI-RS resource set. This set may beused for CM, and additional DCI bits indicate ZP/NZP CSI-RS resources asIMR. This disclosure contemplates the configuration and indication forCMR/IMR/CQI measurement/reporting/rate matching being performed in anysuitable manner, according to particular implementations.

Certain embodiments described above refer to the energy/power on an REor associated with a NZP CSI-RS signal on an RE for CM and/or IM. Thisenergy/power may be referred to as energy per resource element (EPRE).Downlink power control may determine the EPRE. The term RE energydenotes the energy prior to cyclic prefix insertion. The term RE energyalso denotes the average energy taken over all constellation points forthe modulation scheme applied. Uplink power control determines theaverage power over an SC-FDMA symbol in which the physical channel istransmitted.

For the purpose of RSRP and RSRQ measurements, the UE may assumedownlink cell-specific RS EPRE is constant across the downlink systembandwidth and constant across all subframes with discovery signaltransmissions until different cell-specific RS power information isreceived.

For a cell that is not a Licensed Assisted Access (LAA) small cell(Scell), the UE may assume downlink cell-specific RS EPRE is constantacross the downlink system bandwidth and constant across all subframesuntil different cell-specific RS power information is received.

The downlink cell-specific reference-signal EPRE may be derived from thedownlink reference-signal transmit power given by the parameterreferenceSignalPower provided by higher layers. The downlinkreference-signal transmit power is defined as the linear average overthe power contributions (in [W]) of all REs that carry cell-specificreference signals within the operating system bandwidth.

For an LAA SCell, the UE may assume that the EPRE of downlinkcell-specific RS in subframe n is same as the EPRE of downlinkcell-specific RS in subframe n−1, if all OFDM symbols of at least thesecond slot of subframe n−1, are occupied.

The ratio of PDSCH EPRE to cell-specific RS EPRE among PDSCH REs (notapplicable to PDSCH REs with zero EPRE) for each OFDM symbol is denotedby either ρ_(A) or ρ_(B) according to the OFDM symbol index as given byTable 2 and Table 3 below.

TABLE 2 OFDM symbol indices within a slot of a non-MBSFN subframe wherethe ratio of the corresponding PDSCH EPRE to the cell-specific RS EPREis denoted by ρ_(A) or ρ_(B) OFDM symbol indices within a OFDM symbolindices within a slot where the ratio of the corresponding slot wherethe ratio of the corresponding PDSCH EPRE to the cell-specific RS PDSCHEPRE to the cell-specific RS EPRE is denoted by ρ_(A) EPRE is denoted byρ_(B) Number of Normal cyclic Extended cyclic Normal cyclic Extendedcyclic antenna ports prefix prefix prefix prefix One or two 1, 2, 3, 5,6 1, 2, 4, 5 0, 4 0, 3 Four 2, 3, 5, 6 2, 4, 5 0, 1, 4 0, 1, 3

TABLE 3 OFDM symbol indices within a slot of an MBSFN subframe where theratio of the corresponding PDSCH EPRE to the cell-specific RS EPRE isdenoted by ρ_(A) or ρ_(B) OFDM symbol indices within a OFDM symbolindices within a slot where the ratio of the corresponding slot wherethe ratio of the corresponding PDSCH EPRE to the cell-specific RS PDSCHEPRE to the cell-specific RS EPRE is denoted by ρ_(A) EPRE is denoted byρ_(B) Normal cyclic Extended cyclic Normal cyclic Extended cyclic Numberof prefix prefix prefix prefix antenna n_(s) mod n_(s) mod n_(s) modn_(s) mod n_(s) mod n_(s) mod n_(s) mod n_(s) mod ports 2 = 0 2 = 1 2 =0 2 = 1 2 = 0 2 = 1 2 = 0 2 = 1 One or two 1, 2, 3, 0, 1, 2, 3, 1, 2, 3,0, 1, 2, 0 — 0 — 4, 5, 6 4, 5, 6 4, 5 3, 4, 5 Four 2, 3, 4, 0, 1, 2, 3,2, 4, 3, 0, 1, 2, 0, 1 — 0, 1 — 5, 6 4, 5, 6 5 3, 4, 5

In addition, ρ_(A) and ρ_(B) are UE-specific.

Embodiments for measurement restriction in time domain for channel andinterference measurement are provided. Taking into account theflexibilities to fit the rich channel conditions in various NRscenarios, measurement restriction by a configurable number of slots canbe considered in NR. Moreover, the change of beamformer may beassociated with certain events, e.g., TRP applying a new beam accordingto the beam indicator (e.g., CRI) or the like reported by the UE. Otherevents include RRC reconfiguration of measurement and/or resources. Whensuch an event occurs, it may be appropriate for the UE to reset itschannel measurement and not average the measurements before and afterthe event. Therefore, time domain channel measurement reset due torelevant events may be supported.

For similar reasons as described above for time domain channelmeasurement restriction, interference measurement restriction by aconfigurable number of slots can be considered in NR, in order to alignwith the possible configuration of time domain channel measurementrestriction.

Therefore, in certain embodiments, a configurable number of slots aresupported for time domain channel/interference measurement restrictionand time domain measurement reset due to a change in CRI and/ormeasurement/resource configurations. In some scenarios, a slot valuerange may include at least {1 slot, unrestricted # of slots}. Linearlyincreasing numbers of slots may be supported, such as {1, n, 2n, 3n, . .. , unrestricted # of slots}, where n=5 or 10. Nonlinearly increasingnumbers of slots may be supported, such as {1, 2, 4, unrestricted # ofslots} for 2 bits or {1, 2, 4, 8, 16, 32, 64, unrestricted # of slots}for 3 bits. Note that the number of slots here is the number of slotswith measurement resources, and excludes slots without measurementresources.

The frequency domain channel measurement restriction, on the other hand,may be considered in situations where multiple services exist indifferent parts of the whole frequency band. While channel measurementover the whole bandwidth is possible, it may be appropriate for certainservices to measure one or a few bandwidth parts for the UE. In thisregard, restricting the channel measurement in frequency domain may bebeneficial.

Multiple bandwidth parts may be configured to a UE, each bandwidth partcorresponding to a specific numerology to support the relevant service.At least one out of multiple bandwidth parts may be activated, whilemultiple bandwidth parts with different numerologies activatedsimultaneously may also be considered. With this flexibility ofbandwidth part configuration, the frequency domain channel measurementrestriction may be applicable in partial bandwidth measurements (e.g.,measurement restricted to one or more bandwidth parts out of the fullbandwidth).

Certain embodiments contemplate further measurement restriction within abandwidth part. For instance, in beam management, a UE-group-specificCSI-RS may cover the whole band of the link or a specific subband. AUE-specific CSI-RS may be allocated within the frequency resources to aparticular UE, in order to provide accurate beam information and/or CSIfor example, and also to avoid affecting other FDM-ed transmissions. Inthis regard, a CSI-RS bandwidth smaller than the bandwidth part may beconsidered, and thus the frequency domain channel measurementrestriction on the CSI-RS configured bandwidth within a bandwidth partmay be appropriate.

CSI-RS may be configured with a bandwidth smaller than the UE'sbandwidth part. In this way, channel measurement resources as well asinterference measurement resources can be configured with theirrespective bandwidth, which can be equal to or smaller than thebandwidth part. For a derived CSI, NZP CSI-RS IMR bandwidth may be thesame as the bandwidth of NZP CSI-RS CMR. Otherwise, it may not bereasonable to calculate CQI based on a NZP CSI-RS CMR configured inbandwidth part 1 but a NZP CSI-RS IMR in bandwidth part 2 for example.Thus, in certain embodiments, a UE might not expect to receive an NZPCSI-RS resource for interference measurement whose bandwidth is not thesame as the bandwidth of channel measurement resource.

Regarding the signaling of measurement restriction via CSI-RS bandwidth,various techniques may be performed. For example, with a granularity ofRBG, a bitmap may be used. The length of the bitmap depends on theRBG/CSI-RS bandwidth and corresponding RBG size. For continuous CSI-RSbandwidth, a starting position and a length of the bandwidth can beconfigured to the UE based on a granularity of RB, for example.

Channel and interference measurement restriction on CSI-RS resourceswithin a configurable number of subbands may be supported, and if theCSI-RS resource has a configured bandwidth smaller than the bandwidthpart, channel and interference measurements may be restricted to theCSI-RS resources within the configured bandwidth.

In certain embodiments, a UE may be assumed to performchannel/signal/RRM/RLM measurements for a CSI report on the RS(including CRS, CSI-RS) resource(s) indicated by dedicated signaling forthe CSI report if the signaling is found, and otherwise on CRS.Furthermore, if a resource-restricted measurement subset is signaled forrestricting signal/channel measurement resources (note that however, in3GPP generally resource-restricted measurements are for restricting theinterference measurement resources, not restricting the signal/channelmeasurement resources), then the UE is assumed to further restrict itssignal/channel measurements within the indicated subset. In anembodiment, an eNB (or other network node) may configure three NZPCSI-RS resources for a UE, and an NZP CSI-RS resource may be assignedwith no CQI report for signal measurements (and possibly no interferencemeasurements). In such a case, the UE is not assumed to performchannel/signal/RRM/RLM measurements (nor interference measurements) onthis resource until otherwise signaled by an eNB (or other networknode). For example, when the UE receives and demodulates/decodes aPDSCH, the UE is assumed to perform rate matching and/or discarding ofthe REs indicated as NZP CSI-RS resources but not linked to any CQI. Onthose REs, the eNB (or other network node) can determine to transmitsignals not limited to the signaled CSI-RS contents, but may choose toblank (e.g., so that a CSI-RS resource from another point/cell maytransmit without interference from this point/cell), or may choose totransmit special signals (e.g., so that a CSI-RS resource from anotherpoint/cell may see the desired interference from this point/cell and aUE can perform the desired interference measurements).

For example, in HetNet Enhanced Inter-Cell Interference Control (eICIC),a pico UE may seek to report a CQI with a macro muting and a CQI with amacro interfering, based on measurements on CSI-RS resources. In certainembodiments, when the UE measures interference on CSI-RS resourcesassociated with macro muting, the macro does not need to be in an almostblank subframe. However, it may be appropriate for the macro to blank onthe corresponding REs and choose to mark these REs as an NZP CSI-RSresource that is not linked to any CQI report so that macro UEs may ratematch around these REs. Similarly, when the UE measures interference ona CSI-RS resource associated with macro interfering, the macro does notneed to be in a non-almost blank subframe. However, the macro maytransmit any chosen signals on the corresponding REs and can choose tomark these REs as an NZP CSI-RS resource that is not linked to any CQIreport so that macro UEs may rate match around these REs.

Similarly, in Further Enhanced Inter-Cell Interference Control (FeICIC),when the pico UE measures interference on a CSI-RS resource associatedwith macro interfering with reduced power, the macro does not need to bein an almost blank subframe, but may transmit at the reduced power onthe corresponding REs. The macro can choose to mark these REs as an NZPCSI-RS resource that is not linked to any CQI report so that macro UEsmay rate match around these REs. Similarly, in Coordinated Beam Blanking(CBB) or other semi-statically configured interference coordinationschemes, when the UE measures interference on a CSI-RS resourceassociated with macro interfering with aspatial/beamforming/beam-blanking pattern, the macro does not need totransmit PDSCH according to the pattern. However, the macro may transmitaccording to the pattern on the corresponding REs and can choose to markthese REs as an NZP CSI-RS resource that is not linked to any CQI reportso that macro UEs may rate match around these REs. In other words,configuring an NZP CSI-RS resource that is not linked to any CQI reportmay allow an eNB to “emulate” or “mock” the desired interference onthose REs without affecting operations of the eNB's UEs. Configuring anNZP CSI-RS resource that is not linked to any CQI report also may allowan eNB to perform an operation on those REs which may be backwardincompatible. In other words, signaling a non-zero-power CSI-RS resourceto a UE which is not used for a CQI report is a way for the network totransparently perform RE muting or interference emulation ornon-compatible transmissions without affecting the UE behavior. Asdescribed below, another way of doing so is to signal a ZP CSI-RSresource to a UE which is not used for a CQI report. A possibleadvantage for using an NZP CSI-RS resource for this purpose is that theNZP CSI-RS resource can be configured more flexibly (e.g., in terms ofperiodicity, subframe offset, number of antenna ports) than the ZPCSI-RS resource, but higher signaling overhead may be involved.

In certain embodiments, a UE may assume that a signaled CSI-RS resourcefor channel/signal measurements for a CSI report corresponds to onechannel/signal condition (within each resource-restricted measurementsubset, if signaled). A CSI-RS resource signaled to a UE forchannel/signal measurements can be associated with a unique CSI-RS indexexplicitly or implicitly. For instance, a CRS resource may be implicitlyindexed as 0. In some embodiments, an eNB (or the network element)allows an NZP CSI-RS resource to be configured with zero (no), one, ormore Pc values. As described above, Pc may be an assumed ratio of PDSCHEPRE to CSI-RS EPRE when UE derives CSI feedback. In certainembodiments, Pc takes values in the range of [−8, 15] dB with 1 dB stepsize, where the PDSCH EPRE corresponds to the symbols for which theratio of the PDSCH EPRE to the cell-specific RS EPRE is denoted byρ_(A), as specified in Table 50.2-2 and Table 50.2-3 of TS 36.213. Inother words, the Pc value may be used by the UE to compute theassociated CQI report, and different Pc values can lead to different CQIfeedback values even if the CQI feedback values are based on commonchannel/signal/interference measurement resources.

When there is a possibility of multiple CQI reports but a same NZPCSI-RS resource is configured for the signal/channel measurements ofthese CQI reports, allowing more than one Pc values to be configured forthe same NZP CSI-RS resource may allow the UE to compute each CQI reportwith the CQI-report-specific Pc value. Another possible advantage ofallowing one or more Pc values to be associated with an NZP CSI-RSresource is that this resource may be used for generating two differentCQI reports for resource-restricted measurements, namely, each CQIreport may be associated with a Pc value. If no Pc value is configuredfor an NZP CSI-RS resource, the UE may be assumed to perform ratematching around the CSI-RS REs. Other ways to signal a UE to performrate matching around the CSI-RS REs may be used, such as a bit toindicate so, or by not linking a CQI report to this CSI-RS resource.

With regard to interference measurements, in 3GPP it was proposed to useeither NZP CSI-RS resources or ZP CSI-RS resources or both forinterference measurement resources. If a ZP CSI-RS resource is to beused for interference measurement, it was generally proposed that eachinterference measurement resource is a 4-RE resource within a ZP CSI-RSresource and is associated with one bit of the 16-bit bitmap of the ZPCSI-RS resource. Such a 4-RE measurement resource unit may be referredto as an interference measurement resource (IMR), or channel-stateinformation interference measurement (CSI-IM) resource, or a ZP CSI-RSresource for interference measurement. In an embodiment, an eNB (orother network node) can allow zero, one, or multiple NZP CSI-RSresources, and/or zero, one, or multiple ZP CSI-RS resources to beconfigured to a UE for interference measurements for CSI feedback bydedicated signaling. In an embodiment, the total number of NZP CSI-RSresources and/or ZP CSI-RS resources for a UE for interferencemeasurements is configured by dedicated signaling. In an embodiment, thetotal number of ZP CSI-RS resources for a UE for interferencemeasurements is configured by dedicated signaling. In an embodiment, thetotal number of ZP CSI-RS resources for a UE (not limited for thepurpose of interference measurements) is configured by dedicatedsignaling. The maximum of any such total number may be predefined instandards specifications or specified as follows.

In another embodiment, the maximum number of NZP CSI-RS resources and/orZP CSI-RS resources for a UE for interference measurements is predefinedin standards specifications, e.g., 2, 3, 4, or more. An eNB/MME/CoMP setcontroller may further limit the actual maximum number via dedicatedsignaling. For example, the standards specification may predefine themaximum to be 4, but a CoMP set controller may signal to the eNBs (orother network nodes) controlled by the CoMP set controller an actualmaximum to be 2. The eNBs (or other network nodes) inform the UEs viadedicated signaling. In another embodiment, no limit to the maximumnumber of NZP CSI-RS resources and/or ZP CSI-RS resources for a UE forinterference measurements is specified/signaled. However, the actualmaximum number of NZP CSI-RS resources and ZP CSI-RS resources for a UEfor interference measurements may be practically limited by, e.g., thetotal number of CSI-RS resources for a UE.

In an embodiment, the total number of NZP CSI-RS resources and/or ZPCSI-RS resources for a UE is configured by dedicated signaling. Inanother embodiment, the maximum number of NZP CSI-RS resources and/or ZPCSI-RS resources for a UE is predefined in standards specifications,e.g., 2, 3, 4, or more. The eNB/MME/CoMP set controller may furtherlimit the actual maximum number via dedicated signaling. For example,the standards specification may predefine the maximum to be 4, but aCoMP set controller may signal to the eNBs (or other network nodes)controlled by the CoMP set controller an actual maximum to be 2. TheeNBs (or other network nodes) inform the UEs via dedicated signaling. Inanother embodiment, no limit to the maximum number of NZP CSI-RSresources and/or ZP CSI-RS resources for a UE is specified/signaled.

As described above, in some embodiments, it may be permissible for theconfiguration of the number of ZP CSI-RS resources for interferencemeasurements to be unrelated to the configuration of the number of ZPCSI-RS resources (which may be used for interference measurements and/orRE muting and/or other purposes). This may be useful since it mayprovide more flexibility to configure ZP CSI-RS resources forinterference measurements and ZP CSI-RS resources for purposes notlimited to interference measurements; however, this may imply separatesignaling of ZP CSI-RS resources for interference measurements and ZPCSI-RS resources.

In some embodiments, an eNB (or other network node) can allow a CSIreport for a UE to be configured with zero, one, or more NZP CSI-RSresources and/or zero, one, or more ZP CSI-RS resources for interferencemeasurements by dedicated signaling. If no or zero CSI-RS resource isconfigured for interference measurements for a CSI report by dedicatedsignaling to a UE, the UE is assumed to perform interferencemeasurements for the CSI report based on CRS.

In an embodiment, a dedicated signaling to configure interferencemeasurements to a UE can be signaled together with CSI-RSconfigurations. For example, in a CSI-RS configuration, a field may beadded to indicate for which CQI report(s) this CSI-RS resource(s) is tobe used for interference measurements. The CQI report(s) may beconfigured in a separate signaling and may be indexed, and theindication can be based on index(es) of the CQI report(s). However, whena CSI-RS resource is changed/added/removed, it may be appropriate toreconfigure the CQI reports. When a CQI report is to bereconfigured/added/removed, it may be appropriate to re-signal theCSI-RS configurations since some CQI configuration information issignaled with a CSI-RS configuration.

In an embodiment, a dedicated signaling to configure interferencemeasurements to a UE can be signaled together with CQI reportconfigurations. For example, in a CQI report configuration, a field maybe added to indicate which (ZP or NZP) CSI-RS resource(s) are to be usedfor interference measurements for this CQI report. The CSI-RSresource(s) to be used for interference measurements may be configuredin a separate signaling and may be indexed, and the indication can bebased on index(es) of the resource(s). In this case, if the CQI reportis reconfigured/added/removed, it may or may not be appropriate tore-signal the CSI-RS configurations. In an embodiment, a dedicatedsignaling to configure interference measurements to a UE can be signaledseparately from CQI/CSI-RS configuration signaling, which may be abitmap linking the CQI reports to the associated CSI-RS resources forinterference measurements, or a bitmap linking the CSI-RS resources forinterference measurements to the associated CQI reports. The indicationcan be based on index(es) of the resource(s) and the index(es) of theCQI report(s). In this case, if the CQI report isreconfigured/added/removed, it may or may not be appropriate tore-signal the CSI-RS configurations.

Further, a UE may be assumed to perform interference measurements for aCSI report on the RS (including CRS, CSI-RS) resource(s) indicated bydedicated signaling for the CSI report if the signaling is found, andotherwise on CRS. Furthermore, if a resource-restricted measurementsubset is signaled, then the UE may be assumed to further restrict itsinterference measurements within the indicated subset. In an embodiment,an eNB (or other network node) may configure three CSI-RS resources fora UE, and a CSI-RS resource may be assigned with no CQI report forsignal measurements and no interference measurements. In such a case,the UE is not assumed to perform any measurements on this resource untilotherwise signaled by an eNB (or other network node).

For example, for PDSCH reception the UE may be assumed to perform ratematching and/or discarding of the REs indicated as resources forinterference measurements but associated with no CQI report. On thoseREs, the eNB can decide to transmit signals not limited to the signaledCSI-RS contents, but may choose to blank (e.g., so that a CSI-RSresource from another point/cell may transmit without interference fromthis point/cell), or to transmit special signals (e.g., so that a CSI-RSresource from another point/cell may see the desired interference fromthis point/cell and a UE can perform the desired interferencemeasurements). If an NZP CSI-RS resource is signaled to a UE forinterference measurements, the UE also may be informed by dedicatedsignaling whether the UE is assumed to remove the signal of that CSI-RSor not when performing interference measurements. This assumption may beindicated using a bit in the dedicated signaling. Further, a CSI-RSresource signaled to a UE for interference measurements can beassociated with a unique CSI-RS index explicitly or implicitly. Forinstance, CRS resource may be implicitly indexed as 0.

With regard to CSI configuration and calculation, an eNB (or anothernetwork node) allows one or multiple CQI reports to be configured for aUE by dedicated signaling. In an embodiment, the total number of CQIreports for a UE is configured by dedicated signaling. In anotherembodiment, the maximum number of CQI reports for a UE is predefined inthe standards specifications, for instance, 2, or 3, or 4, or more CQIreports for a UE. In another embodiment, an eNB does not explicitlyspecify a limit to the maximum number of CQI reports for a UE. In someembodiments, an eNB (or other network node) can allow a CQI report for aUE to be configured, such as via dedicated signaling, to be periodicwith a reporting period, subframe offset, and Physical Uplink ControlChannel (PUCCH) mode, and/or to be aperiodic with a PUSCH mode.

When multiple CQI reports are to be fed back based on multiple CSI-RSresources and possibly CRS resources, it may be appropriate to link aCQI report to the reference signals properly, for instance via dedicatedsignaling. For example, for a UE, an eNB (or other network node) mayallow a CQI report to be configured based on signal/channel measurementsof CRS resources as in Release 10 or signal/channel measurements ofzero, one, or multiple NZP CSI-RS resources, and based on interferencemeasurements of CRS resources as in Release 10 or interferencemeasurements of zero, one, or multiple NZP and/or ZP CSI-RS resources.If the signaling to link CQI with RS for a UE is not found for a CQIreport, the UE may be assumed to compute the CQI report based on CRS.

NZP CSI-RS for IM is supported in Release 15, as a key element tofacilitate probing/pre-scheduling/emulation based link adaptation forMU-MIMO and other applications. One issue is the subband measurementassumption/behavior when NZP CSI-RS for IM is configured, where asubband includes 4, 8, 16, or 32 PRBs depending on the bandwidth andconfiguration. However, the UE pairing and/or NZP CSI-RS rank/precodingmay be generally different for different subbands. For example, eachPrecoding Resource Block Group (PRG) (e.g., including 2 or 4 PRBs orwideband) may have a precoding different from any other PRG. Averagingacross subbands with different UE pairing and/or NZP CSI-RSrank/precoding might not generate any meaningful measurement results fora subband. Thus, in certain embodiments, it may be appropriate toprohibit calculating averages across subbands with different UE pairingand/or NZP CSI-RS rank/precoding.

Although subband CSI reporting is supported (see, e.g., 5.2.1.4 of TS38.214), the standard does not define UE assumptions on the precoding ofthe subbands and also does not regulate UE subband measurement behavior.In other words, for either wideband or subband reporting, typically theUE first generates a measurement for each subband, and then derivesreporting one or more quantities (e.g., CQI) for each subband. In thefirst step, the subband measurement may be generated based on thecurrent subband or multiple subbands, which is not specified in thestandards. Therefore, it is generally up to the UE implementation, andfor some UE implementations, the UE may utilize some other subbands togenerate one subband report, and for some UE implementations, the UE mayutilize some other subbands to generate one subband measurement, whichmay lead to misleading outcomes. The following describes a few possibleembodiments for reducing or eliminating these misleading outcomes.

In an embodiment, if NZP CSI-RS for IM is configured and CQI reportingwithout PMI is configured, the UE may interpret that each subband in theCSI reporting band may be associated with a signal transmissionassumption (associated with the NZP for CM) and an interferencetransmission assumption (associated with the NZP for IM) different fromthose on any other subbands. As a result, the UE would not performprocessing blindly across multiple subbands when estimatingsignal/interference over NZP CSI-RS resources. This embodiment specifiesUE assumptions for its measurement operations.

In an embodiment, the above signal transmission assumption is the UEassumption of NZP port precoding. In other words, if interferencemeasurement is performed on NZP CSI-RS and if the associatedCSI-ReportConfig is configured with the higher layer parameterreportQuantity set to ‘cri-RI-CQI’, the UE may assume, for a subband ofthe CSI reporting band, a precoding matrix is applied to form the portsof the NZP CSI-RS resource different from the precoding matrix on anyother subband of the CSI reporting band, for channel measurement.Likewise, the UE may assume, for a subband of the CSI reporting band, aprecoding matrix is applied to form the ports of the NZP CSI-RS resourcedifferent from the precoding matrix on any other subband of the CSIreporting band, for channel measurement.

In an embodiment, the frequency domain granularity is not subbands, butPRG of the associated DMRS, a bundle of a number (e.g., 2, 4, or 8) ofsubbands, or a number of subbands as signaled by the network. For a UEconfigured with a CSI-ReportConfig with the higher layer parameterreportQuantity set to ‘cri-RI-CQI’, the standard (TS 38.214) specifiesthat, when calculating the CQI for a rank, the UE shall use the portsindicated for that rank for the selected CSI-RS resource, and theprecoder for the indicated ports shall be assumed to be the identitymatrix. This does not contradict the assumption in this embodiment,since the precoding matrix applied to form the ports of the NZP is notnecessarily the precoding matrix assumed by the UE for the ports of theNZP for deriving CQI.

In an embodiment, if NZP CSI-RS for IM is configured and CQI reportingwithout PMI is configured, the UE may interpret that within each subbandin the CSI reporting band there is a signal transmission assumption andan interference transmission assumption. As a result, the UE may performprocessing within one subband when estimating signal/interference overNZP CSI-RS resources. This embodiment specifies UE assumption for itsmeasurement operations. In other words, the UE can assume a commonprecoding for forming the ports of NZP within one subband, and if the UEattempts to incorporate NZP on other subbands to assist the measurementon this subband, the UE has to verify the validity based on the receivedNZP on these subbands. If the UE can infer that multiple subbands havethe same precoding forming the ports, the UE can average/process acrossthese subbands for one subband's measurement, and otherwise the UE willrestrict the measurement based on the NZP in the subband. Similarly asabove, the frequency domain granularity may be different from subbands.Therefore, when a UE is configured with NZP CSI-RS resource setting forinterference measurement and the associated reporting quantity iscri-RI-CQI, the UE may assume, for the PRBs within a subband of the CSIreporting band, a single precoding matrix is applied to form the portsfor the NZP CSI-RS resources for channel measurement, and a singleprecoding matrix is applied to form the ports for the NZP CSI-RSresources for interference measurement.

In an embodiment, if NZP CSI-RS for IM is configured and subband CQIreporting is configured, the UE may interpret that each subband in theCSI reporting band is associated with a signal transmission assumptionand an interference transmission assumption different from those onanother subband. In other words, when a UE is configured with NZP CSI-RSresource setting for interference measurement and cqi-FormatIndicator isconfigured as subbandCQI, the UE may assume different precoding on eachsubband within the CSI reporting band for the NZP CSI-RS resources forchannel measurement and the NZP CSI-RS resources for interferencemeasurement. Additionally or alternatively, the UE may assume that, forthe PRBs within a subband of the CSI reporting band, a single precodingmatrix is applied to form the ports for the NZP CSI-RS resources forchannel measurement, and a single precoding matrix is applied to formthe ports for the NZP CSI-RS resources for interference measurement.Similar as above, the frequency domain granularity may be different fromsubbands.

In an embodiment, UE behavior may be specified to restrict itsmeasurement in frequency domain (e.g., for each subband) according tomeasurement restriction configuration or other configuration combinationsuch as NZP CSI-RS for IM and CQI reporting without PMI. Note that thesubband measurement is applicable to subband reporting and widebandreporting. Therefore, if interference measurement is performed on NZPCSI-RS and if the associated CSI-ReportConfig is configured with thehigher layer parameter reportQuantity set to ‘cri-RI-CQI’, a UE mayrestrict its measurement within each subband of the CSI reporting bandfor the NZP CSI-RS resource for channel measurement and the NZP CSI-RSresources for interference measurement. In this context, restrictionrefers to the measurement resources within a subband that can be used toderive the measurement result for that subband.

In an embodiment that can be combined with any of the above embodiments,if there may be an issue regarding the subband measurement accuracy dueto the low density of NZP CSI-RS, the network may configure the largersubband size (e.g., eight PRBs in a subband rather than four PRBs in asubband). The network may restrict probing to performing probing withthe larger PRG size (e.g., four PRBs). Furthermore, a bundle of a number(e.g., 2, 4, or 8) of subbands may be pre-specified, or a bundle of anumber (e.g., 2, 4, or 8) of subbands may be determined by the densityof the NZP (e.g., equal to N/density, where N may be 12 or 24 associatedwith DMRS density), or a number of subbands as signaled by the networkassociated with a reporting configuration, based on which the above UEassumptions or UE frequency-domain measurement restriction is applied.

In an embodiment that can be combined with any of the above embodiments,the combination of configuration conditions leading to the above UEassumptions or UE behavior may be replaced by one or more thefollowing: 1) a signaling (RRC, MAC, or DCI) that specifies aprobing/pre-scheduling mode, such as linking the reporting to aPDSCH/DMRS, signaling designed above for probing, etc.; 2) a signaling(RRC, MAC, or DCI) that specifies a subband (or any other granularity infrequency domain) measurement assumption; 3) a signaling (RRC, MAC, orDCI) that specifies a subband (or any other granularity in frequencydomain) reporting; 4) interference measurement that is performed on NZPCSI-RS; 5) a CSI-ReportConfig that is configured with the higher layerparameter reportQuantity set to ‘cri-RI-CQI’; 6) aperiodic CSI-RS; 7)aperiodic CSI reporting; or 8) a signaling (RRC, MAC, or DCI) thatspecifies a subband (or any other granularity in frequency domain)measurement restriction. In certain embodiments, the subband UEassumption or UE behavior may be applied to interference measurement,channel/signal measurement only, or both (which may use one or twosignaling as given above, for example, one for both channel andinterference, or one for channel and the other for interference).

FIG. 27 illustrates an example method 2700 in which a combination of UEbehaviors is implemented, according to certain embodiments of thisdisclosure. The method begins at step 2702. NZP CSI-RS for IM isconfigured and CQI reporting without PMI is configured subband CQIreporting is configured,

At step 2704, the UE determines whether it is configured with a firstconfiguration. In certain embodiments, the first configuration is usingNZP CSI-RS for interference measurement. If the UE determines that it isnot configured with the first configuration (e.g., that NZP CSI-RS forIM is not configured), then at step 2706, the UE applies a wideband UEassumption/no restriction, as described above.

Returning to step 2704, if the UE determines that it is configured withthe first configuration (e.g., that NZP CSI-RS for IM is configured),then the UE proceeds to step 2708.

At step 2708, the UE determines whether it is configured with a secondconfiguration. In certain embodiments, the second configuration is CQIreporting without PMI. As another example, the second configurationcould be subband CQI reporting. If the UE determines that it is notconfigured with the second configuration (e.g., that CQI reportingwithout PMI is not configured or that subband CQI reporting is notconfigured), then the method proceeds to step 2706 at which the UEapplies a wideband UE assumption/no restriction, as described above.

Returning to step 2708, if the UE determines that it is configured withthe second configuration (e.g., that CQI reporting without PMI isconfigured or that subband CQI reporting is configured), then the UEproceeds to step 2710. At step 2710, the UE applies a subband UEassumption/restriction, as described above.

Although particular configurations are described for the first andsecond configurations, this disclosure contemplates any suitableconfigurations, such as those described above, as being the first andsecond configurations. Additionally, although the particularconfigurations described with reference to the method of FIG. 27 aredesignated as the first and second configurations, this disclosurecontemplates reversing which of these configurations is the first andwhich is the second, as appropriate. Furthermore, the example methodshow in FIG. 27 includes the combination of two configurations. Thisdisclosure, however, contemplates a UE being implemented with oneconfiguration or multiple configurations (different than or in additionto those described with reference to method 2700), including any of thepossible above-described configurations. The associated embodimentsubband UE assumption, UE behavior, and measurement restriction are alsolisted above.

In an embodiment, if a sounding reference signal (SRS) is associatedwith an NZP CSI-RS resource via spatialRelationInfo, then the subbandmeasurement applied to the NZP leads to subband precoding of the SRS,with the same frequency-domain granularity.

In an embodiment, if reportQuantity is set to ‘cri-RI-CQI’, a rankindicator (RI) restriction may be signaled. The RI restriction can be a8-bit bitmap configured in CSI-ReportConfig to specify which rank(s) ofrank 1 to rank 8 is selected, where the i-th bit (from 0 to 7) is forrank i+1. The UE performs measurements for the allowed RIs and does notperform measurements for other RIs (e.g., the ports/layers associatedwith the bitmap location set to be 1 are used by the UE). Based on thesemeasurements, the UE selects one RI and associated CRI/RI to report. TheRI restriction bitmap may be a new field in CSI-ReportConfig, or mayreuse the typeI-SinglePanel-ri-Restriction in CodebookConfig (the UEignore other fields in CodebookConfig). Multiple CSI-ReportConfig may beassociated with the same PortIndexFor8Ranks if they are based on thesame NZP, but each has its own RI restriction to specify differentranks, which saves signaling overhead.

FIG. 28 illustrates an example method 2800 for wireless communication,according to certain embodiments of this disclosure. For purposes ofthis example, a UE is described as performing the steps of method 2800.The method begins at step 2802.

At step 2804, the UE receives an indication of a set of NZP CSI-RSresources for channel measurement (CM) and interference measurement(IM). As an example, the indication of the set of NZP CSI-RS resourcesfor CM and IM may be received by the UE from a network node, such as aNodeB, an eNB, a gNB, or any other suitable type of network node. Afirst subset of the set of NZP CSI-RS resources may be configured forCM, and a second subset of the set of NZP CSI-RS resources may beconfigured for IM. In certain embodiments, the indication of the set ofNZP CSI-RS resources for CM and IM includes an indication the firstsubset of the set of NZP CSI-RS resources configured for CM and thesecond subset of the set of NZP CSI-RS resources configured for IM. Asdescribed above, the first subset of the NZP CSI-RS resources and thesecond subset of the NZP CSI-RS resources might or might not overlap.

In certain embodiments, the UE receives (e.g., from the network node)the indication of the first subset of the NZP CSI-RS resources and thesecond subset of the NZP CSI-RS resources via DCI. Additionally oralternatively, the UE may receive (e.g., from the network node) theindication of the first subset of the NZP CSI-RS resources and thesecond subset of the NZP CSI-RS resources via a combination of DCI andMAC signaling. In certain embodiments, the DCI provides a dynamictriggering of one or more CSI reporting settings.

At step 2806, the UE receives a configuration of a set of resources forCSI-IM, which may affect the assumptions made by the UE for interferencemeasurement. This disclosure further contemplates the UE receiving(e.g., from a network node) a configuration of a measurement restrictionassociated with channel measurement, receiving (e.g., from a networknode) a configuration of a measurement restriction associated withinterference measurement, or receiving (e.g., from a network node) botha configuration of a measurement restriction associated with channelmeasurement and a configuration of a measurement restriction associatedwith interference measurement.

At step 2808, the UE performs a channel measurement on the first subsetof the set of NZP CSI-RS resources. To the extent the UE received (e.g.,from a network node) a configuration of a measurement restrictionassociated with channel measurement, the channel measurement performedat step 2808 may be performed in accordance with the receivedconfiguration of the measurement restriction associated with the channelmeasurement. The channel measurement may be performed in associationwith a CSI report.

At step 2810, the UE performs an interference measurement on at leastthe second subset of the set of NZP CSI-RS resources. The second subsetof the set of NZP CSI-RS resources may include one or more NZP CSI-RSports. In certain embodiments, the UE performs the interferencemeasurement according to one or more assumptions.

As a first example assumption, the UE may perform the interferencemeasurement according to an assumption that each NZP CSI-RS port in thesecond subset of the set of NZP CSI-RS resources corresponds to aninterference transmission layer, and the interference measurement may bein accordance with a set of energy per resource element (EPRE) ratioseach associated with one NZP CSI-RS resource in the second subset of theset of NZP CSI-RS resources. In certain embodiments, each EPRE ratio inthe set of EPRE ratios that are each associated with one NZP CSI-RSresource in the second subset of the set of NZP CSI-RS resourcesspecifies an assumed ratio of a PDSCH EPRE to an EPRE of an NZP CSI-RSsignal on the NZP CSI-RS resource.

As a second example assumption, the UE may perform the interferencemeasurement according to an assumption that other interference notassociated with an interference transmission layer to which an NZPCSI-RS port in the second subset of the set of NZP CSI-RS resourcescorresponds is on the first subset of the set of NZP CSI-RS resourcesand the second subset of the set of NZP CSI-RS resources.

As a third example assumption, to the extent the UE received aconfiguration of a set of resources for CSI-IM (e.g., at step 2806), theUE may perform the interference measurement according to an assumptionthat other interference not associated with an interference transmissionlayer to which an NZP CSI-RS port in the second subset of the set of NZPCSI-RS resources corresponds is on the set of resources for CSI-IM.

Furthermore, the UE may perform the interference measurement inaccordance with any suitable combination of the described assumptions aswell as other assumptions.

To the extent the UE received (e.g., from a network node) aconfiguration of a measurement restriction associated with interferencemeasurement, the interference measurement performed at step 2810 may beperformed in accordance with the received configuration of themeasurement restriction associated with the interference measurement.The interference measurement may be performed in association with a CSIreport.

At step 2812, the UE may generate a CSI report based on the channelmeasurement (e.g., performed at step 2808) and the interferencemeasurement (e.g., performed at step 2810). In certain embodiments, theCSI report includes at least a CQI but not a PMI. It should be noted,however, that this disclosure contemplates the CSI report including anysuitable combination of information, including a PMI if appropriate.

At step 2814, the UE may transmit the CSI report to the network. Forexample, the UE may transmit the CSI report to a network node, whichmight or might not be the same network node that transmitted the set ofNZP CSI-RS resources to the UE at step 2804.

At step 2816, the method ends.

FIG. 29 illustrates an example method 2900 for wireless communication,according to certain embodiments of this disclosure. For purposes ofthis example, a network node is described as performing the steps ofmethod 2900. For example, the network node may be a NodeB, an eNB, agNB, or any other suitable type of network node. The method begins atstep 2902.

At step 2904, the network node may indicate to a UE a set of NZP CSI-RSresources for channel measurement (CM) and interference measurement(IM). A first subset of the set of NZP CSI-RS resources may beconfigured for CM, and a second subset of the set of NZP CSI-RSresources may be configured for IM. In certain embodiments, theindication of the set of NZP CSI-RS resources for CM and IM includes anindication the first subset of the set of NZP CSI-RS resourcesconfigured for CM and the second subset of the set of NZP CSI-RSresources configured for IM. As described above, the first subset of theNZP CSI-RS resources and the second subset of the NZP CSI-RS resourcesmight or might not overlap.

In certain embodiments, the network node communicates (e.g., to the UE)the indication of the first subset of the NZP CSI-RS resources and thesecond subset of the NZP CSI-RS resources via DCI. Additionally oralternatively, the network node may communicate (e.g., to the UE) theindication of the first subset of the NZP CSI-RS resources and thesecond subset of the NZP CSI-RS resources via a combination of DCI andMAC signaling. In certain embodiments, the DCI provides a dynamictriggering of one or more CSI reporting settings. Although particulartechniques for the network node to indicate the set of NZP CSI-RSresources, the first subset of the set of NZP CSI-RS resources, and thesecond subset of the set of NZP CSI-RS resources are described, thisdisclosure contemplates the network node indicating these resources tothe UE in any suitable manner.

At step 2906, the network node indicates to the UE a configuration of aset of resources for CSI-IM, which may affect the assumptions made bythe UE for interference measurement.

At step 2908, the network node determines whether to provide ameasurement restriction associated with channel measurement, ameasurement restriction associated with interference measurement, orboth.

If the network node determines at step 2908 to provide a measurementrestriction, then at step 2910 and depending on the type of measurementrestriction the network node determines to issue, the network nodeindicates one or more configurations of one or more suitable types ofmeasurement restrictions. For example, if the network node determines atstep 2908 to provide a measurement restriction associated with channelmeasurement, then at step 2910, the network node indicates to the UE aconfiguration of a measurement restriction associated with channelmeasurement. As another example, if the network node determines at step2908 to provide a measurement restriction associated with interferencemeasurement, then at step 2910, the network node indicates to the UE aconfiguration of a measurement restriction associated with interferencemeasurement. As another example, if the network node determines at step2908 to provide both a measurement restriction associated with channelmeasurement and a measurement restriction associated with interferencemeasurement, then at step 2910, the network node indicates to the UEboth a configuration of a measurement restriction associated withchannel measurement and a configuration of a measurement restrictionassociated with interference measurement.

Returning to step 2908, if the network node determines not to provide ameasurement restriction, then the method proceeds to step 2912.

At step 2912, the network node receives from the UE a CSI report. Thereceived CSI report is based on the channel measurement and interferencemeasurement performed by the UE in response to the indication by thenetwork node to the UE of NZP CSI-RS resources at step 2904.

For example, the UE may have performed the channel measurement on thefirst subset of the set of NZP CSI-RS resources. To the extent thenetwork node indicated to the UE a configuration of a measurementrestriction associated with channel measurement, the channel measurementperformed by the UE may have been performed in accordance with theindicated configuration of the measurement restriction associated withthe channel measurement.

As another example, the UE may have performed the interferencemeasurement on at least the second subset of the set of NZP CSI-RSresources. The second subset of the set of NZP CSI-RS resources mayinclude one or more NZP CSI-RS ports. In certain embodiments, the UE mayhave performed the interference measurement according to one or moreassumptions.

As a first example assumption, the UE may have performed theinterference measurement according to an assumption that each NZP CSI-RSport in the second subset of the set of NZP CSI-RS resources correspondsto an interference transmission layer, and the interference measurementmay be in accordance with a set of energy per resource element (EPRE)ratios each associated with one NZP CSI-RS resource in the second subsetof the set of NZP CSI-RS resources. In certain embodiments, each EPREratio in the set of EPRE ratios that are each associated with one NZPCSI-RS resource in the second subset of the set of NZP CSI-RS resourcesspecifies an assumed ratio of a PDSCH EPRE to an EPRE of an NZP CSI-RSsignal on the NZP CSI-RS resource.

As a second example assumption, the UE may have performed theinterference measurement according to an assumption that otherinterference not associated with an interference transmission layer towhich an NZP CSI-RS port in the second subset of the set of NZP CSI-RSresources corresponds is on the first subset of the set of NZP CSI-RSresources and the second subset of the set of NZP CSI-RS resources.

As a third example assumption, to the extent the network node indicateda configuration of a set of resources for CSI-IM (e.g., at step 2906),the UE may have performed the interference measurement according to anassumption that other interference not associated with an interferencetransmission layer to which an NZP CSI-RS port in the second subset ofthe set of NZP CSI-RS resources corresponds is on the set of resourcesfor CSI-IM.

Furthermore, the UE may perform the interference measurement inaccordance with any suitable combination of the described assumptions aswell as other assumptions.

To the extent the network node indicated to the UE (e.g., at step 2910)a configuration of a measurement restriction associated withinterference measurement, the interference measurement performed by theUE may have been performed in accordance with the indicatedconfiguration of the measurement restriction associated with theinterference measurement.

In certain embodiments, the CSI report includes at least a CQI but not aPMI. It should be noted, however, that this disclosure contemplates theCSI report including any suitable combination of information, includinga PMI if appropriate.

At step 2914, the network node may transmit data in accordance with thereceived CSI report. For example, based on information included in theCSI report received from the UE, the network node may select appropriateresources for communicating with the UE.

At step 2916, the method ends.

Although this disclosure describes particular components as performingparticular operations for the various methods and process described inthis disclosure, this disclosure contemplates other componentsperforming those operations. Additionally, although this disclosuredescribes or illustrates particular operations for the various methodsand process described in this disclosure as occurring in a particularorder, this disclosure contemplates any suitable operations occurring inany suitable order. Moreover, this disclosure contemplates any suitableoperations being repeated one or more times in any suitable order.Although this disclosure describes or illustrates particular operationsfor the various methods and process described in this disclosure asoccurring in sequence, this disclosure contemplates any suitableoperations occurring at substantially the same time, where appropriate.Any suitable operation or sequence of operations described orillustrated herein may be interrupted, suspended, or otherwisecontrolled by another process, such as an operating system or kernel,where appropriate. The acts can operate in an operating systemenvironment or as stand-alone routines occupying all or a substantialpart of the system processing.

FIG. 30 illustrates an example communication flow showing MU-MIMO linkadaptation based on NZP CSI-RS for interference measurement, accordingto certain embodiments of this disclosure. The illustrated exampleincludes three timelines 3002, a timeline 3002 a for a first UE 3004 a(UE1), a timeline 3002 b for a gNB 3006, and a timeline 3002 c for asecond UE 3004 b (UE2). Although gNB 3006 is described as a gNB, thisdisclosure contemplates gNB 3006 being any suitable type of networknode.

UE1 transmits a CQI report to gNB 3006 at 3008 a, and UE2 transmits aCQI report to gNB 3006 at 3008 b. gNB 3006 performs multi-user pairingat 3010. At 3012 (at time n), gNB 3006 probes UE1 and UE2, includingtransmitting appropriate resources for channel measurement andinterference measurement to UE1 and UE2. For example, gNB transmits NZPCSI-RS resources for interference measurement (NZP IMR 3014 a) and NZPCSI-RS resources for channel measurement (NZP CMR 3016 a) to UE1 andtransmits NZP CSI-RS resources for interference measurement (NZP IMR3014 b) and NZP CSI-RS resources for channel measurement (NZP CMR 3016b) to UE2. As described above, various measurement restrictions alsocould be indicated by gNB 3006 as part of the probing process.

In response to the interference and channel measurement resources, UE1and UE2 perform CQI derivation 3022 a and 3022 b, respectively. This CQIderivation includes performing respective channel measurements andinterferences measurements using the indicated resources indicated at3012 (probing). As described above, the interference measurements may beperformed according to one or more assumptions.

UE1 transmits another CQI report to gNB 3006 at 3024 a, and UE2transmits another CQI report to gNB 3006 at 3024 b. Based on theinformation received in the CQI reports at 3024, gNB 3006 performsmulti-user transmission 3026. The transmission may be a PDSCH. At 3028 aand 3028 b, respectively, UE1 and UE2 may receive the PDSCH transmission(at time n+k).

In the illustrated example, the interference measurement resources attime n reflect multi-user interference at time n+k. The channelmeasurement resources 3016 a for UE1 are the interference measurementresources 3014 b for UE2. Furthermore, the NZP CSI-RS for interferencemeasurement at time n is a pre-coded reference signal from an interferer(inter-cell or intra-cell), reflecting interference at time n+k.

Embodiments of this disclosure may provide one or more technicaladvantages. In certain embodiments, configuring NZP CSI-RS resources forinterference measurement provides improved link adaptation performance.Certain embodiments facilitate use of a higher spectrum frequency.Certain embodiments provide improved performance that is suitable foruse with multiple-input and multiple-output (MIMO) and massive MIMOsystems. Link adaptation according to certain embodiments of thisdisclosure allows interference measurement resources at a time, n, toreflect multi-user interference at a time n+k, with a channelmeasurement resource of a first UE being an interference measurementresource of a second UE, which may be advantageous in a multi-user MIMOsystem. Certain embodiments may improve performance in carrieraggregation/channel aggregation and in coverage enhancement.

FIG. 31 is a block diagram of a processing system 3100 that may be usedfor implementing the system, apparatuses, devices, and methods disclosedherein, according to certain embodiments of this disclosure.

Specific devices may utilize all of the components shown, or only asubset of the components, and levels of integration may vary from deviceto device. Furthermore, a device may contain multiple instances of acomponent, such as multiple processing units, processors, memories,transmitters, receivers, etc. The processing system may comprise aprocessing unit 3102 equipped with one or more input/output devices,such as a speaker, microphone, mouse, touchscreen, keypad, keyboard,printer, display, and the like. Processing unit 3102 may include acentral processing unit (CPU) 3104, memory 3106, a mass storage device3108, a video adapter 3110, and an I/O interface 3112 connected to abus.

The bus may be one or more of any type of several bus architecturesincluding a memory bus or memory controller, a peripheral bus, videobus, or the like. CPU 3104 may comprise any type of electronic dataprocessor. Memory 3106 may comprise any type of system memory such asstatic random access memory (SRAM), dynamic random access memory (DRAM),synchronous DRAM (SDRAM), read-only memory (ROM), a combination thereof,or the like. In an embodiment, memory 3106 may include ROM for use atboot-up, and DRAM for program and data storage for use while executingprograms.

Mass storage device 3108 may comprise any type of storage deviceconfigured to store data, programs, and other information and to makethe data, programs, and other information accessible via the bus. Massstorage device 3108 may comprise, for example, one or more of a solidstate drive, hard disk drive, a magnetic disk drive, an optical diskdrive, or the like.

Video adapter 3110 and the I/O interface 3112 provide interfaces tocouple external input and output devices to the processing unit 3102. Asillustrated, examples of input and output devices include a display 3114coupled to video adapter 3110 and a mouse/keyboard/printer 3116 coupledto I/O interface 3112. Other devices may be coupled to the processingunit 3102, and additional or fewer interface cards may be utilized. Forexample, a serial interface card (not shown) may be used to provide aserial interface for a printer.

Processing unit 3102 also includes one or more network interfaces 3118,which may comprise wired links, such as an Ethernet cable or the like,and/or wireless links to access nodes or different networks 3120.Network interface 3118 allows processing unit 3102 to communicate withremote units via networks 3120. For example, network interface 3118 mayprovide wireless communication via one or more transmitters/transmitantennas and one or more receivers/receive antennas. In an embodiment,processing unit 3102 is coupled to a local-area network or a wide-areanetwork for data processing and communications with remote devices, suchas other processing units, the Internet, remote storage facilities, orthe like.

An embodiment processing system for performing methods described herein,which may be installed in a host device. The processing system mayinclude a processor, a memory, and interfaces. The processor may be anycomponent or collection of components adapted to perform computationsand/or other processing related tasks, and the memory may be anycomponent or collection of components adapted to store programmingand/or instructions for execution by the processor. In an embodiment,the memory includes a non-transitory computer readable medium. Theinterfaces may be any component or collection of components that allowthe processing system to communicate with other devices/componentsand/or a user. For example, one or more of the interfaces may be adaptedto communicate data, control, or management messages from the processorto applications installed on the host device and/or a remote device. Asanother example, one or more of the interfaces may be adapted to allow auser or user device (e.g., personal computer (PC), etc.) tointeract/communicate with the processing system. The processing systemmay include additional components not depicted in the figure, such aslong term storage (e.g., non-volatile memory, etc.).

In some embodiments, the processing system is included in a networkdevice that is accessing, or part otherwise of, a telecommunicationsnetwork. In one example, the processing system is in a network-sidedevice in a wireless or wireline telecommunications network, such as abase station, a relay station, a scheduler, a controller, a gateway, arouter, an applications server, or any other device in thetelecommunications network. In other embodiments, the processing systemis in a user-side device accessing a wireless or wirelinetelecommunications network, such as a mobile station, a user equipment(UE), a personal computer (PC), a tablet, a wearable communicationsdevice (e.g., a smartwatch, etc.), or any other device adapted to accessa telecommunications network.

In some embodiments, one or more of the interfaces connects theprocessing system to a transceiver adapted to transmit and receivesignaling over the telecommunications network.

In some embodiments, a transceiver adapted to transmit and receivesignaling over a telecommunications network is provided. The transceivermay be installed in the host device. The transceiver comprises anetwork-side interface, a coupler, a transmitter, a receiver, a signalprocessor, and a device-side interface. The network-side interface mayinclude any component or collection of components adapted to transmit orreceive signaling over a wireless or wireline telecommunicationsnetwork. The coupler may include any component or collection ofcomponents adapted to facilitate bi-directional communication over thenetwork-side interface. The transmitter may include any component orcollection of components (e.g., up-converter, power amplifier, etc.)adapted to convert a baseband signal into a modulated carrier signalsuitable for transmission over the network-side interface. The receivermay include any component or collection of components (e.g.,down-converter, low noise amplifier, etc.) adapted to convert a carriersignal received over the network-side interface into a baseband signal.The signal processor may include any component or collection ofcomponents adapted to convert a baseband signal into a data signalsuitable for communication over the device-side interface(s), orvice-versa. The device-side interface(s) may include any component orcollection of components adapted to communicate data-signals between thesignal processor and components within the host device (e.g., theprocessing system, local area network (LAN) ports, etc.).

The transceiver may transmit and receive signaling over any type ofcommunications medium. In some embodiments, the transceiver transmitsand receives signaling over a wireless medium. For example, thetransceiver may be a wireless transceiver adapted to communicate inaccordance with a wireless telecommunications protocol, such as acellular protocol (e.g., long-term evolution (LTE), etc.), a wirelesslocal area network (WLAN) protocol (e.g., Wi-Fi, etc.), or any othertype of wireless protocol (e.g., Bluetooth, near field communication(NFC), etc.). In such embodiments, the network-side interface comprisesone or more antenna/radiating elements. For example, the network-sideinterface may include a single antenna, multiple separate antennas, or amulti-antenna array configured for multi-layer communication, e.g.,single input multiple output (SIMO), multiple input single output(MISO), multiple input multiple output (MIMO), etc. In otherembodiments, the transceiver transmits and receives signaling over awireline medium, e.g., twisted-pair cable, coaxial cable, optical fiber,etc. Specific processing systems and/or transceivers may utilize all ofthe components shown, or only a subset of the components, and levels ofintegration may vary from device to device.

It should be appreciated that one or more steps of the embodimentmethods provided herein may be performed by corresponding units ormodules. For example, a signal may be transmitted by a transmitting unitor a transmitting module. A signal may be received by a receiving unitor a receiving module. A signal may be processed by a processing unit ora processing module. Other steps may be performed by an indicatingunit/module, a measuring unit/module and/or a determining unit/module.The respective units/modules may be hardware, software, or a combinationthereof. For instance, one or more of the units/modules may be anintegrated circuit, such as field programmable gate arrays (FPGAs) orapplication-specific integrated circuits (ASICs).

While this disclosure has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of thedisclosure, will be apparent to persons skilled in the art uponreference to the description. It is therefore intended that the appendedclaims encompass any such modifications or embodiments.

For example, the various elements or components may be combined orintegrated in another system or certain features may be omitted, or notimplemented. In addition, techniques, systems, subsystems, and methodsdescribed and illustrated in the various embodiments as discrete orseparate may be combined or integrated with other systems, modules,techniques, or methods without departing from the scope of thisdisclosure. Other items shown or described as coupled or directlycoupled or communicating with each other may be indirectly coupled orcommunicating through some interface, device, or intermediate componentwhether electrically, mechanically, or otherwise. Other examples ofchanges, substitutions, and alterations are ascertainable by one skilledin the art and could be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. A method for wireless communications, the methodcomprising: receiving, by a user equipment (UE), control information ofa first subset of a set of non-zero-power (NZP) channel stateinformation (CSI) reference signal (CSI-RS) (NZP CSI-RS) resources and asecond subset of the set of NZP CSI-RS resources, the second subset ofthe set of NZP CSI-RS resources comprising one or more NZP CSI-RS ports,the control information being associated with a CSI report; performing,by the UE, a channel measurement on the first subset of the set of NZPCSI-RS resources; performing, by the UE, an interference measurement onat least the second subset of the set of NZP CSI-RS resources inaccordance with each NZP CSI-RS port in the second subset of the set ofNZP CSI-RS resources corresponding to a corresponding interferencetransmission layer, and in accordance with other interference notassociated with any of corresponding interference transmission layers,the other interference being on at least the second subset of the set ofNZP CSI-RS resources; generating, by the UE, the CSI report based on thechannel measurement and the interference measurement; and transmitting,by the UE, the CSI report to a network.
 2. The method of claim 1,wherein the control information associated with the CSI report alsoincludes a set of resources for CSI-IM.
 3. The method of claim 2,wherein the other interference being on at least the second subset ofthe set of NZP CSI-RS resources and the set of resources for CSI-IM, theother interference on the set of resources for CSI-IM not beingassociated with any of the corresponding interference transmissionlayers corresponding to the second subset of the set of NZP CSI-RSresources.
 4. The method of claim 1, wherein the control informationexcludes a set of resources for CSI-IM, and the CSI report is notassociated with any set of resources for CSI-IM.
 5. The method of claim1, wherein the interference measurement is further in accordance withother interference on the first subset of the set of NZP CSI-RSresources, the other interference on the first subset of the set of NZPCSI-RS resources not being associated with any of the correspondinginterference transmission layers corresponding to the second subset ofthe set of NZP CSI-RS resources.
 6. The method of claim 1, wherein theCSI report comprises at least a channel quality indicator (CQI) andexcludes a precoding matrix indicator (PMI).
 7. The method of claim 1,further comprising: receiving a configuration of measurement restrictionassociated with channel measurement.
 8. The method of claim 1, whereinthe first subset of the set of NZP CSI-RS resources and the secondsubset of the set of NZP CSI-RS resources overlap.
 9. The method ofclaim 1, further comprising: receiving, by the UE from a network node, asignaling of the set of NZP CSI-RS resources for the channel measurementand the interference measurement.
 10. The method of claim 1, furthercomprising: receiving, by the UE from a network node, a signalingindicating the first subset of the set of NZP CSI-RS resources, thesecond subset of the set of NZP CSI-RS resources, and the CSI report.11. The method of claim 10, wherein the signaling is received viadownlink control information (DCI).
 12. The method of claim 11, whereinthe DCI provides a triggering of one or more CSI reporting settings. 13.The method of claim 10, wherein the signaling is received via mediaaccess control (MAC) signaling.
 14. The method of claim 1, wherein theinterference measurement is further performed in accordance with energyper resource element (EPRE) ratios associated with the second subset ofthe set of NZP CSI-RS resources.
 15. The method of claim 14, whereineach of the EPRE ratios specifies a corresponding ratio of acorresponding physical downlink shared channel (PDSCH) EPRE to acorresponding NZP CSI-RS EPRE of the second subset of the set of NZPCSI-RS resources.
 16. A user equipment (UE), comprising: one or moreprocessors; and a non-transitory computer-readable storage mediumstoring programming for execution by the one or more processors, theprogramming including instructions to cause the UE to: receive controlinformation of a first subset of a set of non-zero-power (NZP) channelstate information (CSI) reference signal (CSI-RS) (NZP CSI-RS) resourcesand a second subset of the set of NZP CSI-RS resources, the secondsubset of the set of NZP CSI-RS resources comprising one or more NZPCSI-RS ports, the control information being associated with a CSIreport; perform a channel measurement on the first subset of the set ofNZP CSI-RS resources; perform an interference measurement on at leastthe second subset of the set of NZP CSI-RS resources in accordance witheach NZP CSI-RS port in the second subset of the set of NZP CSI-RSresources corresponding to a corresponding interference transmissionlayer and in accordance with other interference not associated with anyof corresponding interference transmission layers, the otherinterference being on at least the second subset of the set of NZPCSI-RS resources; generate the CSI report based on the channelmeasurement and interference measurement; and transmit the CSI report toa network.
 17. The UE of claim 16, wherein the control informationassociated with the CSI report also includes a set of resources forCSI-IM.
 18. The UE of claim 17, wherein the other interference being onat least the second subset of the set of NZP CSI-RS resources and theset of resources for CSI-IM, the other interference on the set ofresources for CSI-IM not being associated with any of the correspondinginterference transmission layers corresponding to the second subset ofthe set of NZP CSI-RS resources.
 19. The UE of claim 16, wherein thecontrol information excludes a set of resources for CSI-IM, and the CSIreport is not associated with any set of resources for CSI-IM.
 20. TheUE of claim 16, wherein the UE further performs the interferencemeasurement in accordance with other interference on the first subset ofthe set of NZP CSI-RS resources, the other interference on the firstsubset of the set of NZP CSI-RS resources not being associated with anyof the corresponding interference transmission layers corresponding tothe second subset of the set of NZP CSI-RS resources.
 21. The UE ofclaim 16, wherein the CSI report comprises at least a channel qualityindicator (CQI) and excludes a precoding matrix indicator (PMI).
 22. TheUE of claim 16, wherein the programming further includes instructions tocause the UE to: receive a configuration of measurement restrictionassociated with channel measurement.
 23. The UE of claim 16, wherein thefirst subset of the set of NZP CSI-RS resources and the second subset ofthe set of NZP CSI-RS resources overlap.
 24. The UE of claim 16 whereinthe programming further includes instructions to cause the UE to:receive, from a network node, a signaling of the set of NZP CSI-RSresources for the channel measurement and the interference measurement.25. The UE of claim 16, wherein the programming further includesinstructions to cause the UE to: receive, from a network node, asignaling indicating the first subset of the set of NZP CSI-RSresources, the second subset of the set of NZP CSI-RS resources, and theCSI report.
 26. The UE of claim 25, wherein the signaling is receivedvia downlink control information (DCI).
 27. The UE of claim 26, whereinthe DCI provides a triggering of one or more CSI reporting settings. 28.The UE of claim 25, wherein the signaling is received via media accesscontrol (MAC) signaling.
 29. The UE of claim 16, wherein the UE furtherperforms the interference measurement in accordance with energy perresource element (EPRE) ratios associated with the second subset of theset of NZP CSI-RS resources.
 30. The UE of claim 29, wherein each of theEPRE ratios specifies a corresponding ratio of a corresponding physicaldownlink shared channel (PDSCH) EPRE to a corresponding NZP CSI-RS EPREof the second subset of the set of NZP CSI-RS resources.